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184 Cards in this Set
- Front
- Back
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Circadian rhythm?
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Last about 24 hours. Such as the sleep-wake cycle and body temp.
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Hormones, for circadian rhythm?
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Cortisol is lowest around 6.00am and is produced when we are stressed, but is also related to making us alert when we wake up.
Melatonin and growth hormones peak at about midnight. |
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Core body temperature for circadian rhythm?
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Lowest at about 4.30am and highest at around 6.00pm.
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What are biological clocks?
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Groupings of interacting molecules in cells throughout the body.
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What is the master clock?
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Group of nerve cells in the brain called the suprachaismatic nucleus, which contains 20,000 nerve cells and is located in the hypothalamus.
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Does the make and keep its own circadian rhythm?
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Produced by natural factors within the body, also affected by signals from the environment.
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How do circadian rhythms affect body functions?
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Can change sleep-wake cycles, hormones release, and body temp.
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Internal factors?
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Endogenous pacemakers.
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External factors?
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Exogenous zeitgebers.
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Infradrian rhythm?
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repeats more than once a day, but less than once a year.
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Menstrual cycle?
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28 days, human women, Regulates ovulation. 15 days in ovulation, and egg is released from ovary. Female is most fertile as progesterone levels increase after ovulation and thickens the lining of the uterus to prepare for pregnancy. Lining shreds if no pregnancy.
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Biological rhythm?
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Innate biologically driven behaviour that is periodically repeated.
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SCN?
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Small cluster of neurons in the hypothalamus buried deep in the brain, and have an intrinsic activity rhythm.
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Circadian rhythm- evaluation- individual differences?
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Individual differences exist in sleep/wake cycles. Duffy et al. found that early risers prefer 6.00am to 10.00pm and later rises prefer 10.00am to 1.00am.
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Validity- case study of Siffre?
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Its the study of one individual and therefore has unique features. His body behaviour may of not been typical of all people. Also living in a cave may have affects as it is cold.
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Biological approach- circadian rhythm?
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Studies are typical of the biological approach to understanding behaviour, they propose that human behaviour can be explained in terms of structures in the brain and in terms of hormonal activity. However, human behaviour is more complex than this, as people can override biologically determined behaviours.
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McClintock study of menstrual cycle?
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29 women aged 20-35, irregular spontaneous ovulation.
Cotton pads placed under other women's arms at different times during their menstrual cycle after bathing with unperfumed products = sweat donors. After pads were treated with alcohol and frozen to disguise. Pads wiped under the noses of the 20 women on a daily basis. |
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McClintock results?
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68% responded to pheromones presented and their menstrual cycles either shortened by 1-14 days or lengthened by 1-12 days.
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McClintock conclusion?
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It is still unclear how the pheromones trigger menstrual cycle changes.
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McClintock evaluation - conflicting evidence?
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A study that examined women's basketball for an extended period of time found no correlation between the women's menstrual cycle patterns. Known that exercise can cause change in menstrual cycles and may of affected any possible synchronisation.
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McClintock evaluation- Animal evidence?
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An ovulating female boar, when exposed to a male boars saliva, immediately goes into a spread-legged mating posture.
Humans do not do this however. It is hard to generalise. Overrides biological instincts. - free will - help control desire. |
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McClintock evaluation- Methodological issues?
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Errors of self-report my affect validity, for example women saying when their menstrual cycle started. EV's were controlled and therefore improves reliability.
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Peter Tripp?
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Stayed awake for 201 hours for charity and
continued performing on the radio. After three days he began to be abusive to other people. By day five he had begun to experience hallucinations. His body had begun to enter REM sleep while awake, which is known as REM intrusions. |
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Peter Tripp? ( After experiment)?
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He slept for 24 hours and then claimed to feel like normal. However was reported to not be the same and split form his wife.
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Peter Tripp ( REM and REM rebound)?
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Body was willing to put in danger by entering REM sleep while awake. REM is essential for the body, and the research supports this.
He slept for 24 hours, as the body makes up for the lost hours of sleep, so it can catch up on REM. You however would of expected a greater number of hours for REM rebound to occur, as he lost a significant amount of sleep. |
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Peter Tripp- Gender Bias?
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Womens bodies may react differently. For example there was a reported decrease in body temperature, women may be able to control this more, or may be more effected due to menstrual cycle effects.
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Peter Tripp- Validity?
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His brain was not constantly monitored, over time of 201 hours, therefore there could have been occasions in which he was not being monitored and he unknowingly entered REM sleep, and therefore this experiment not valid to study sleep deprivation as it as low levels of control.
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Rechtshaffen?
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Study on rats, to see how they would react to no sleep.
Placed on a rotating disc so they remained physically active. When they began to fall asleep, they fell into the water. After 33 days all rats died. Sleep is essential for survival. |
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Rechtshaffen-cause and effect?
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Unable to identify a cause and effect as they would have suffered severe levels of stress which could of been identified as the cause of death rather than the lack of sleep.
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Rechtshaffen- Animal study?
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Cannot be generalised to humans. Looking at a biological perspective there is a high percentage of DNA shared with rats and humans, we are both mammals and have similar brain structures.
On the other hand humans have higher cognitive functions, as we are more socially developed. Our brains are more complex and we may suffer from negative effects more quickly. |
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Rechtshaffen? - ethical issues
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It is better to not use humans as are considered more valuable and contribute more to society.
Rats are still sentient beings, they feel pain and have the right to live. Looking at the three R's they have mostly all been ticked off. They have not replaced the use of animals with other techniques but they have refined to make the animals suffer as little as possible and reduced by keeping the numbers to a minimum. They would have had to of met most standards to be approved. |
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Restoration theory- biological approach?
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It is reductionist in a number of ways. Firstly it does not account for individual differences in sleep; if it has a biological function it would be expected that most people sleep for around the same time, whereas actually there is a wide variation between individuals in the amount of REM sleep per night.
Secondly if sleep has biological functions, it would be expected that there would be more similarity between humans and animals, than there is and less wide variation between different species, such as dolphins who have no REM sleep. |
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Restoration theory- Slow wave sleep?
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Growth hormone is secreted during SWS. So is very important during childhood. Also in adulthood for protein synthesis and regrowth.
Growth hormone is secreted and stimulate growth. |
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Restoration theory- REM sleep ( Brain growth)
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REM sleep is far higher in babies than adults. REM sleep is proportional to the immaturity of offspring. For example human babies sleep for most the day and has a lot of REM sleep. whereas dolphins have no REM sleep and can swim from birth. This shows that REM sleep and neural development have a relationship.
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Restoration theory- SWS- The immune system?
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Lack of SWS has been associated with reduced functioning of the immune system- the body's system of defence against viruses and bacteria. The immune system consists of various protein molecules- antibodies- which are regenerated during cell growth and protein synthesis during SWS.
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Restoration theory- REM sleep (neurotransmitters)
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REM sleep allows for a break in neurotransmitters, which enables neurones to regain sensitivity, so they body can function properly.
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Restoration theory- REM sleep (memory)?
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Consolidation of procedural memory occurs, which is related to things like riding a bike.
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Restoration theory- SWS (memory)?
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When consolidation of semantic and episodic memory occurs, related to knowledge and memory for events.
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Exercise and need for sleep?- restoration theory?
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Increased exercise should lead to increased sleep to restore proteins and biochemical used.
Shapiro found that runners in a marathon race slept for about an hour more on the two night following the race, SWS increased in particular. |
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Restoration theory- case studies?
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Because these are unique studies, you are unable to apply to the general population because there may be individual differences. They were both motivated for the fact that they were doing it for charity, others who are not may not be able to stay awake for so long.
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Peter Tripp and Randy Gardner- Methodology issues?
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The experiment was not double blind and therefore there may be demand characteristics, with the hallucinations and aggression they may of knew that they were being watched and therefore acted this way to benefit the results.
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Randy Gardner?
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Stayed awake 264 hours.
Hallucinations and aggressive (moody) Forgot what he was saying (memory lapses) Slurred speech. Confusion and dizziness. 14 hour catch up. Highly motivated. |
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Energy conservation- Evolutionary explanation?
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Sleep serves the purpose of providing as a period of enforced inactivity, therefore using much less energy. Warm blood animals expand a lot of energy to maintain temperature and therefore sleep more, such as humans. Cold blooded animals on the other do not expand energy for temperature regulation.
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Evolutionary explanation- Foraging requirements?
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Time spent sleeping may be constrained by food requirements. Herbivores spend time eating grass etc. which is relatively poor in nutrients. Cannot afford to spend time sleeping.
Animals like dogs and cats have high nutrient food and therefore can 'afford' to rest. |
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Evolutionary explanation- predator avoidance?
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If an animal is a predator then they can sleep for longer, whereas prey must remain vigilant to avoid predators, and are best to sleep when least vulnerable.
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Evolutionary explanation- Waste of time?
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Suggested that sleep helps animals to stay out of the way of predators during the day when they are most vulnerable. For most animals this means sleeping during the hours of darkness.
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Evolutionary explanation- Siegel?
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Being awake is riskier than being asleep, sleep enables energy conservation and keeping an individual out of danger.
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Zepelin and Rechtshaffen?
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Small animals sleep longer than larger animals, with the exception of sloths, which sleep for 20 hours a day.
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Zepelin and Rechtshaffen- conclusion?
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Contradicts the predator avoidance part of the evolutionary theory. You would expect smaller animals to be prey and the large animals to be predators.
You would expect smaller animals to sleep for a shorter amount of time to avoid predators. Support the idea however that energy conservation is a main reason for sleep. Small animals have high metabolic rates and therefore use up more energy, and need to rest to conserve this. |
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Allison and Chichetti?
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Animals with higher risk of predation sleep less generally but rabbits sleep as much as moles even though their risk of predation is much higher. Rabbits may have an extremely high metabolic rate and therefore have to sleep to conserve their energy.
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Allison and chichetti? -evaluation
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39 species were used in the lab study, therefore due to a small number of species use, it is not representative of the animals kingdom.
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Allison and Chichetti? -evaluation?
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The data found was correlational and not causal, therefore a cause and effect cannot be established, although the study was done in a lab, meaning there were high levels of control.
As you are unable to establish a cause and effect you cannot say whether animals with higher risks of predation sleep less. |
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Capellini et al.- Found a negative correlation between metabolic rate and sleep?
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This negative correlation between metabolic rate and sleep contradicts the energy conservation, as you would expect those with a high metabolic rate to have more sleep, as during sleep they would have a period of inactivity while sleeping, in which energy is not expanded.
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Capellini et al- Neg correlation eval?
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They used standardised procedures e.g only picked data from animals habituated to lab conditions. Therefore there is high control within the data picked, making it more valid.
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Capellini et al.- Foraging requirements and sleep?
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Greater foraging requirements creates a constraint on time available for sleeping.
Supports the foraging requirements. As an animal has to gather food, such as herbivores that spend their time eating plants that is relatively poor in nutrients. So they must spend more time eating, and therefore cannot 'afford' to spend time sleeping. |
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Evolutionary theory- reductionist?
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The approach is reductionist as it reduces complex behaviours to adaptiveness. However the approach also considers many ecological and physiological factors, reducing the criticism somewhat.
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Evolutionary theory- Free will and determinism?
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Sleeping behaviour is seen as being caused by past environments, therefore there is no free will.
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What is insomnia?
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This is a difficulty in getting to sleep and/or staying asleep.
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Secondary insomnia?
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This is caused by an underlying medical condition. For example someone who has depression may have the symptom of insomnia, or people who do shift work.
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Primary insomnia?
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Insomnia occurs with no known cause, for example bad sleeping habits that are developed , such as staying up too late to do work.
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Factors that affect insomnia?- Age?
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Those who are older and women are more likely to suffer from insomnia. The reasoning behind this is that older people are more likely to suffer from arthritis which is painful and can be disruptive to sleep. Also as you get older your levels of melatonin can decrease, and even by the age of 60 can be not released at all.
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Factors that affect insomnia?- Gender?
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Women are more likely to suffer from insomnia, this is due to age-related hormone fluctuations. Hormones can change body temperatures, which affects sleep. Therefore things like the menstrual cycle may cause a disruption of sleep and increase the likelihood of developing insomnia.
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Factors that affect insomnia?-Sleep apnoea?
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This is when you stop breathing while you are asleep, which can startle you awake. The pauses may last from a few seconds to minutes and may occur five to thirty times a night.
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What personality factors are thought to increase the risk of suffering insomnia?
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Insomniacs were more likely to internalise psychological disturbance rather acting out problems or being aggressive. The researchers in this study proposed that internalisation leads to higher levels of emotional arousal and increased likelihood of feeling anxious, and it is this that is a risk factor for insomnia.
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Why it is important to distinguish between primary and secondary?
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It is important implications for treatment. If insomnia is the symptom of another disorder, it is important to treat the disorder rather than the symptom of insomnia.
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Hyper arousal?
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High physiological arousal.
Being alert and perceptive. In a version of flight and fight response where their brain sends signals of impending danger and they need to be on guard. Increases heart rate, body temperature, and metabolic rate and cortisol. Affects sleep because body is alert. |
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Hyper arousal- Bonnett and Arand?
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Found objectively defined insomniacs had a nocturnal increase in metabolic rate.
Nocturnal increase remained even after metabolic values from periods during the night containing wake time or arousal were eliminated from the data set. Chronic insomniacs suffer from a more general disorder of hyper arousal that may be responsible for both the daytime and nocturnal poor sleep. |
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Roberts- Teenage insomnia?
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Teenage insomnia is a major problem.
4,000 11-17 years old from Houston Texas studied. 25% of sample reported of insomnia. Supports both secondary and primary insomnia ( Depression could be a cause and bad sleeping habits also). Growth hormone released (Phase delay syndrome) Prevalent throughout different life stages. |
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Roberts- Teenage insomnia-cultural bias?
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The study was conducted in America.
Different cultures have different attitudes to sleep and therefore you would expect different results. For example in countries that are hot like Spain, they have an afternoon nap when the sun is at its highest point. Therefore they have already had some sleep. |
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Roberts-teenage insomnia- Self report?
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Self report methods were used and therefore there could be social desirability bias to some extend, some may not want to admit to insomnia and others may feel they have it when they do not. This can cause the validity of the research to decrease, as there may not be a truth to the results.
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Watson et al. - Insomnia?
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Found that genetic factors explained 50% of the differences in the risk of developing insomnia, through studying twins. Although this shows that genetics factors play a part in the developing of the disorder, only half is accounted for, therefore you would have to assume that something else is responsible for the other 50%.
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Watson et al. - Insomnia- Reductionist?
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If insomnia as all down to genetics you would expect that genetic factors explained 100% of the differences in the risk od developing insomnia.
It therefore does not account for other factors and only considers the biological approach. |
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Insomnia- Genes and environment interaction- diathesis stress model?
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Environmental factors must be involved. The genetics are a vulnerability that are triggered by an environmental stressor.
You have a vulnerability (Genetics) and an environmental stressor triggers the disorder to develop. |
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Nature Vs nurture- Insomnia?
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When looking at genetics and environment being interwoven together to explain a disorder we can look at the nature vs. nurture debate. Rather than the disorder being caused by one or the other, they are both together causing the disorder. Nature loads the gun and the environment pulls the trigger.
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What are the symptoms of jet lag?
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Tiredness
Problems with attention and concentration Irritability Anxiety |
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Phase delay? - Jet lag?
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The biological clock is ahead of time and it has to wait for external cues to catch up. Like travelling from London to new York.
East to west. |
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Phase advance? - Jet lag?
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Travelling from west to east.
Jet lag symptoms are worse. Biological clock is behind of time. |
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Why do jet lag symptoms occur?
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The SCN take time to adapt to changes. It takes one day to adjust per hour of differences.
Evolutionary explanation- Had time to adapt over 100 years ago because you travelled on horse or foot which was a lot slower than travelling by plane. The SCN has time to adapt. |
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Jet lag symptoms could be cause by what?
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Annoying people.
Anxiety. Adrenaline release. Different altitude. Dehydration. |
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Jet lag- Cho?
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Studies of cabin crew have found they have raised levels of stress hormones and do less well on memory tests than control participants. More dramatically, female cabin crew with years of exposure to long-haul jet travel were found have similar symptoms and some shrinkage of brain structure in the temporal lobe.
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Jet lag- Cho - Not representative?
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The cabin crew travel more frequently than 'normal' people there are more serious consequences than we would expect from one long haul flight.
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Jet lag- Cho - Lack of control?
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There is a lack of control over other factors such as air pressure, oxygen levels rather than just controlling the time changes. You are unable to see a cause and effect, as there are extraneous variables.
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Recht et al. - Jet lag?
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Found over a three year period American baseball teams won 37 percent of games when travelling from West to east and 44 percent after travelling from east to west.
Performance was effected worse after phase advance than after phase delay, as predicted. |
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Recht et al. - jet lag - uncontrolled variables?
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The relative ability of the different teams.
Fluctuations in form, The effect of injury to individual players. |
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Recht et al.- jet lag - unrepresentative?
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They are professional sportsmen and therefore they are fit and healthy, and probably more capable of adapting to time zone changes.
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Recht et al.- Gender bias?
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It does not account differences in women. Women might be affected differently due to hormone fluctuations and body temperature changes.
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Waterhouse et al. - jet lag?
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In a review of over 500 articles on aviation and health, the found that disrupted sleep and hormone patterns led to cabin crew experiencing decreased cognitive performance and mental health problems, including brief episodes of psychosis, while female cabin crew complained of menstrual cycle problems.
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Jet lag- Individual differences?
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Individual differences in biological rhythms make some people more or less sensitive to jet lag. This may be related to genetic influences, such as the circadian clock gene.
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Jet lag- age?
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Age also seems to affect our sensitivity to jet lag, although studies are inconsistent. Some find that the effects of jet lag decrease with age while others find the opposite.
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Real-life application?
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Research into disruption and the interaction between biological clocks and zetigeber light can be used to devise method to reduce the effects of jet lag.
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Methods to reduce jet lag- melatonin?
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Melatonin plays a crucial role in the SCN-pineal system that controls biological rhythms. It has shown that melatonin can reduce the symptoms of jet lag. However depends on phase advance and phase delay and where in the circadian rhythm it is given.
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Methods to reduce jet lag- Exposure to bright light and adapting to local zeitgebers?
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Exposure to bright light can shift circadian rhythms if used at the appropriate points in the circadian cycle.
Immediately adapting to zeitgebers such as time of day and mealtimes. May require use of mild stimulants. |
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Shift patterns?
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12-4 are most difficult hours to work through, low body temperatures and low levels of cortisol. More likely to have an accident as you are less alert.
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Consequences of shift work- Tilly and Wilkinson?
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Despite sleeping through the day night shift workers often suffer from sleep deprivation. This is because they lose two hours of sleep every night because sleep during the day is disrupted by daylight, noises etc that would normally be exogenous zeitgebers to wake us up.
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Soloman- shift work implications to social life?
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Found a 60% divorce rate among night shift workers concluding sleeping during the day makes it hard to spend time with family required to maintain a marriage. However those with weak family ties may choose to do night shifts, and therefore a causal relationship cannot be drawn.
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Knuttsson et al?- Shift work?
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Found that working on the night shift for more than 15 years increases the risk of heart disease.
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Hexheimer and pertri- shift work- melatonin?
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Reviewed 10 studies and found that taking melatonin before bed can help because it makes you more sleepy. Other research showed reduced levels of melatonin may be implicated in incidence of breast cancer in night shift workers though Spiegel attributes the cancer to disruption in release of cortisol.
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Bolvin?- shift work?
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31 male participants and they were exposed to five hours of 'dim light' 'Ordinary light' 'Bright light' or 'Very bright light'
The core body temperature was used to assess the Circadian rhythm. Dim light delayed them by an hour as did ordinary light. Bright light and Very bright light advanced it by five hours. |
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Bolvin?-Shift work- eval?
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Control of the extraneous variables means that there is validity in the results, as there is truth.
It also lacks mundane realism, as it is not a real environment. The number of male samples was relatively small and therefore is not generalizable. |
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Bolvin? Shirt work- applications?
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Can be applied to hospitals to help doctors and nurses to help adapt to shift work.
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Shift work and real life application?
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Chernobyl disaster happened at 1.30am where shift worker failed to notice key warning signals. This is when we would predict attention levels to be at their worst as workers fight off the drive to sleep.
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Czeisler- study of a Utah chemical plant?
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Workers were on traditional type of shift, with three eight hour shifts, on a backward rotation of one week on each shift. Workers reported feeling stressed and having problems with sleep.
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Czeisler recommendations?
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Moving to a forward rotation
One week was not long enough to resynchronise and recommended a three week shift pattern |
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Effects of shift pattern change?
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Adopted recommendations and after nine months on the shift pattern they were reassessed.
Reported fewer health problems and lower stress levels . |
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Nature of sleep- infancy?
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16 hours a day.
Wake every hour or so Quiet sleep is SWS Active sleep is REM More active sleep |
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Nature of sleep- childhood?
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12 hours a day
REM activity is 30% of sleep time Parasomniacs occur EEG patterns look like those of an adult |
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Nature of sleep adolescence?
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9/10 hours sleep
Awake later at night and have more difficulty getting up |
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Nature of sleep- adulthood?
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8 hours a day.
25% REM sleep Insomnia and sleep apnoea May have nap in day 20% REM when old 0-5% SWS when old Older people have phase advance |
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New born babies-life span changes?
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Adaptive mechanisms to make parents life easier.
Daytime sleeping means parents can get on with chores. Night waking has adaptive benefits too. Babies have small stomachs and need to be Fed regularly. Greater amount of REM/ active sleep may be explained in terms of |
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Decoursey- Chipmunks?
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Chipmunks were taken out of their natural environment and placed into one group of out a possible three. The first group were a control group who had nothing done to them. The second group had a lesion on their SCN and the third group has a lesion on the head as if they had the SCN lesion.
The third group is also a control group, to make sure the trauma is not the cause of the results. |
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Decoursey- Chipmunks? Results?
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They were placed back in their habitat and it was found that the chipmunks whose SCN had been damaged were awake longer and in turn were killed by predators as they were up late at night.
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Siffre?- Biological rhythms?
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Stayed in caves over his lifetime to study his circadian rhythm. One particular study he did he spent a long period of time in a cave with no natural light, clocks or any other cues.
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SIffre- biological rhythms-results?
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When he emerged he though it was the 20th of august, when it was really the 17th of September. Without EZ's his sense of time was distorted, therefore this suggests that perception of time is effected by external cues. His rhythm settled at around 24 hours suggesting the EP's were affecting the circadian rhythm. It did fluctuate up to 48 hours. This shows that EZ's are important in helping EP's to regulate a 24 hour rhythm.
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Decoursey- Strong evidence?
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Chipmunks are diurnal which is the same as humans and share a high proportion of DNA with humans,
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Decoursey- Not generalizable?
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They live in different habitats, have different biological systems and humans have a higher cognitive function. Due to these differences, it would be hard to generalise this study to humans from animals, meaning that EP's could play more of a role in animals circadian rhythms but not for humans.
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Decoursey- More cognitively complex?
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Humans are more cognitively complex and therefore the way in which our body would react to a lesion could be extremely different to that of the animals. For example we are already more able to override biological urges to sleep,
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Decoursey- Different habitats?
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Different habitats as well which may also affect our response. Using chipmunks to explain our reaction to a lesion of the SCN would be a reductionist approach, as it ignores the complexity that the human mind is.
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Siffre- Gender bias?
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Women's circadian rhythm could be altered by their infradrian rhythm of the menstrual cycle, due to the fact that their body temperature changes. It is therefore less generalizable and it is not as supportive of the idea that EZ's are important in helping EP's to regulate a 24 hour cycle.
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SIffre- age bias?
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He obtained different results over the years as he aged, showing that each result applies to each different age he was at, individual differences of age may affect how our CR's are affected by EP's and EZ's
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EP's and EZ's - conjoined twins?
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Although they share the same blood and environment it was found one could be asleep and the other not. This shows that something other than EP's and EZ's are acting in this.
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Conjoined twins- free will?
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The other twin may of wanted to be awake, and supports the notion of free will. We can choose when we are asleep and when we are awake and can override biological factors, however we cannot do this indefinitely as you will enter dream sleep while awake.
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Conjoined twins- generalizable?
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This study would not be generalizable to the general population due to the fact that the twins are unique, and they may work in a different way to the general population.
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EP's and EZ's- Free will vs determinism?
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EP's and EZ's may contribute to our circadian rhythms, but ultimately we can override these biological factors, and choose when we are awake or sleep. Therefore supportive of the cognitive approach as this says that individuals determine their way of behaviours due to thought.
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Decoursey-determinism?
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Individual behaviour is supportive of determinism because it is influenced by internal or external forces, rather than the will do something. Chipmunks would not be able to keep themselves awake willing like humans, due to the difference in cognitive ability.
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Siffre- free will?
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If he felt he wanted to the study to go a certain way he would have been able to influence this, for example by staying awake.
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Endogenous pacemaker?
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The SCN plays a critical part in the sleep wake cycle. The light lessens, which the optical nerves from the eyes respond to and send to the SCN. The SCN responds by informing the pineal gland which increases the production of melatonin, which makes us tired.
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Exogenous Zeitgeber?
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The main one is light, and when this lessens we respond by feeling more tired. Another couple of EZ's are social cues and noise. We also have the EZ of the seasons, as we enter winter, the night will being to get darker earlier, and this cues us to go to sleep, as the photoreceptors in our eyes responds to the lessening of light to keep us in rhythm with the external world.
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Nature Vs. Nurture debate for EP's and EZ's?
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Biological clocks are innate mechanisms with a clear genetic component. which emphasises nature over nurture. It is difficult for us to change our sleep/waking patterns.
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Morgan- Mutant hamsters?
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The SCN from mutant hamsters bred to show a circadian rhythm of 20 hours was transplanted into normal hamsters. The normal hamsters subsequently showed the mutant rhythm.
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Morgan- Mutant hamsters- What does this study suggest about the SCN?
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It is essential to the control of the circadian rhythm, as when it is the mutated it alters the time span of the circadian rhythm.
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Morgan- ethical issues?
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It is ethical because the damage to the hamster is outweighed by the relevant research.
However you could consider it unethical as the hamsters then had a mutant SCN which could affect the sleep. |
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What is narcolepsy?
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This is a disorder of the sleep wake cycle which results in excessive and often a loss of muscle tone resulting in cataplexy
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Narcolepsy symptoms?
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Excessive daytime sleepiness.
When you try to stay awake you are faced with involuntary attacks of sleep, which can strike at any time. These can have knock on effects with memory loss, focusing of eyes and tiredness. |
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Explanations for Narcolepsy- REM?
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A malfunction in the system that regulates REM sleep, which explains symptoms like cataplexy (when we enter REM sleep muscle tone is lost and we are effectively paralysed) which accompanies REM sleep and the intrusion of REM- type sleep into daytime sleep.
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Explanations for Narcolepsy- HLA?
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Auto immune disease (HLA complex gene)
Narcoleptics have a mutated gene in chromosome 6 and this causes their immune system to recognise hypocretin as foreign and destroy it. Hypocretin maintains wakefulness. |
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Explanations for narcolepsy- Hypocretin?
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A gene that controls the activity of a brain neurotransmitter called hypocretin, to maintain wakefulness is reduced in people with narcolepsy.
There is also a reduction in hypocretin producing cells in the hypothalamus. |
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Vogel- Narco patient? (REM) + Eval.
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Observed REM sleep at the onset of sleep in a narcoleptic patient.
However, because this was just the one patient it would unique and not generalizable to the general population. |
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Siegel- Dogs with narcolepsy?
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Studied dogs with narcolepsy and recorded neuron activity in the brainstem of narcoleptic dogs that showed that cataplexy is linked to the activations of cells that in normal animals are active only during REM sleep.
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Siegel- eval?
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This may not be generalizable to humans because this is a study of animals. Humans are more cognitively complex and therefore our neuron activity may be considerably different.
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Narcolepsy- biological explanations?
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This only looks at the biological side of narcolepsy and doesn't consider that personality factors may affect the onset of narcolepsy and their symptoms.
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Nishino?
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Found that human narcoleptics have lower levels of hypocretin in cerebrospinal fluid. However low levels of hypocretin are unlikely to be due to inherited factors because human narcolepsy doesn't run in families and it has not been found to be concurrent in twins, where one has the disorder.
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Nishino- backed up by thannick?
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Examined brains of four narcoleptic patients who has died 4-12 years earlier.
It as found that there were between 85-95% less hypocretin neurones in the brain in comparison to 12 brains of people who had not suffered with narcolepsy. |
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Thannick- Objectively measured?
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No possibilities of demand characteristics as the research has been obtained biologically.
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Diathesis stress model- Narcolepsy?
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This is an interaction between environmental factors and a predisposition which makes you vulnerable such as genetics. Both the twins could carry the gene, but only one experiences the environmental stressor which causes the condition to develop.
A virus could trigger a genetic predisposition for narcolepsy. |
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Injection of hypocretin?
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Injection of hypocretin into dogs reversed their narcolepsy, showing the influence of neurotransmitters in the development of the disorder. However these findings cannot be generalised to humans as the human condition seems to have environmental as well as genetic causes.
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Lehrman and Weiss?
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Most explanations of narcolepsy are biological, however there is an alternative explanation that there may be a psychological cause. Sudden attacks of sleepiness might be disguising sexual fantasises.
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Narcolepsy- HLA link?
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The specific HLA variant found most commonly in narcoleptics is not found in all narcoleptics and is also reasonably common in the general population. Which means that HLA cannot be the sole explanation.
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Ultradrian rhythm?
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Biological cycles lasting less than 24 hours, like the cycle of the brain activity during sleep.
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Sleep stages?
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Stage one- Alpha waves disappear and are replaced by low voltage slow waves. Heart rate declines and muscles relax. This is light sleep.
Stage two- Short bursts of sleep spindles are noticeable as well as sharp rises and falls in amplitude known as k complexes. Bodily functions slow down and blood pressure decreases. Stage three- Sleep becomes increasingly deeper and people are difficult to wake. Sleep spindles decline being replaced by long, slow delta waves. Heart rate, blood pressure and temperature decline. Stage four- Deep sleep, where delta waves increase and metabolic rate is low. People are difficult to wake. REM is the last stage of sleep. |
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Dement and Kleitman- method?
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9 Participants, seven adult males and two females.
Five were studied intensively. While only a small amount of data was collected on the two to back up the findings of the main five. They monitored electrical activity in the brain during sleep using an EEG recordings and so could wake participants during the different stages of sleep. |
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Dement and Kleitman- findings?
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People awakened during REM sleep reported dreaming 90% of the time. Dreams were recalled in detail including elaborate visual images, only 7% of awakenings from NREM lead to dream recall.
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Dement and Kleitman- conclusions?
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The point of dreaming was discovered in the ultradian cycle. Nearly all dream recall in NREM awakenings occurred within eight minutes of REM, suggesting that the dream might have been remembered from the previous REM.
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Dement and Kleitman- Ecological validity?
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Artificial surroundings of sleep laboratories, as they would of had electrodes to have to be worn, which suggests that findings may lack ecological validity.
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Dement and Kleitman- Standardised procedures?
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EEG is an objective measurement of studying sleep behaviour and therefore makes the results more valid, as the results have truth to them, as there is no form of bias present.
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Dement and Kleitman- Self report?
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When recalling the dreams, they could say that they had been dreaming and made something up because they knew what was expected of them. They also could of forgot the dream and felt bad and therefore made it up.
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Klein and Armitage?
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They tested participants on verbal and spatial tasks, finding that performance was related to a 96 minute cycle, very similar to the sleep cycle.
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Dement and Kleitman- Nature of sleep?
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It did show a close correlation REM and dreaming, but the nature of relationship remains unclear. It may be that dreams are recalled easier in REM than NREM sleep because the latter is a deeper stage of sleep – perhaps dreams occur in deeper sleep, but are more difficult to recall from it.
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Aschoff and Weber?
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Placed participants in a bunker with no natural light. They settled into a sleep/wake cycle of between 25 and 27 hours, suggesting that endogenous pacemakers control the sleep/wake cycle in the absence of light cues and that light seems necessary to coordinate the biological clock with the external environment.
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Folkard?
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Isolated 12 participants from natural light for 3 weeks, manipulating the clock, so that only 22 hours passed a day. Of the 12 participants, 11 kept pace with clock, showing the strength of the circadian rhythm as a free running cycle.
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Circadian rhythm- biological approach?
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They propose that human behaviour can be explained in terms of the structures in the brain and in terms of hormonal activity. Human behaviour is more complex than this because people can override biologically determined behaviours by making choices about what to do.
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Circadian rhythm- determinism?
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Sometimes it is not possible to override biological factors. For example a blind man had a circadian rhythm of 24.9 hours. He was exposed to various exogenous zeitgebers such as clocks and social cues, yet found great difficulty in reducing his internal pace. So he had to take stimulants in the morning and sedatives at night.
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Circadian rhythm- individual differences?
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Circadian cycles in different people can vary from 13 to 65 hours, and that individual differences between when the circadian rhythm peaks. For example some people prefer to rise early and got to bed early, and some prefer to rise late and go to bed late.
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Life span changes- adolescence?
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Change in sleep pattern linked to changes in hormone production.
Hormones primarily released at night, so sleep patterns are disturbed leading to sleep deprivation. Sleep deprivation 'typical' of puberty irritability, moodiness, changes in school performance and changes in motivation. |
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Crowley et al, 2007, life span changes?
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Hormonal changes can also explain the upset to the circadian rhythm clock, which has been described as a delayed sleep phase syndrome.
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Wolfson and Carskadon?
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Have recommended that school should start later to accommodate the poor attention span of adolescents in the early morning.
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Dement?
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Reported that over 40% of a group of healthy men and women ages 65 to 88 had some form of sleep apnoea, the majority being frequent 'micro-arousal' which are unremembered brief awakenings lasting 3 seconds or less.
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Circadian rhythm- cultural bias?
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Studies were based on western cultures. Tynjala et al found that there were variations in the amount of sleep from on culture to another. People in Asia tended to sleep less than those in Europe suggesting cultural differences in circadian rhythms.
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Circadian rhythm- free will?
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Circadian rhythms are not under the complete control of endogenous pacemakers and it is people themselves that can override this. Behaviour is explained with the biological approach, however human behaviour is more complex, and we can override biologically determined behaviours, as we have free will and can make choices.
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Issue with isolation studies- Circadian rhythm?
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There are normally only a few participants which makes a generalisation to the public problematic, as they are not representative.
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Circadian rhythm- Nature?
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Internal biological clocks control us due to genetics pre-determining our sleep/wake patterns and circadian rhythm being set at around the 24 hour mark.
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Circadian rhythm- Nurture?
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Our behaviour is simply adapted in accordance to the environment and our 24 hour circadian rhythm is because of the external environment cues, like the level of light.
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Circadian rhythm- Nature Vs Nurture?
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The circadian rhythm is biological in nature, however it also requires external cues like light to regulate itself and establish a regular pattern. This is probably why when endogenous pacemakers are removed there Is a problem maintaining the circadian rhythm and the same with the exogenous zeitgebers.
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Seasonal affective disorder?
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This is when people become depressed during the winter months and recover during the summer. Hormones such as melatonin and serotonin are secreted when it is dark. Lack of these hormones can cause depression.
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Seasonal affective disorder- Real world application?
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The role of darkness in SAD has led to development of treatments such as phototherapy. This uses very strong levels of light in the evening or early morning to change levels of melatonin and serotonin.
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Seasonal affective disorder- just circadian disruption?
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Seasons changing from summer to winter for example in the UK could disrupt the circadian rhythm. People still get up at the same time, but go to bed earlier as its darker.
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Infradrian rhythm- PMS- legal defence?
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PMS has been used as a legal defence- in one case a Ms English drove her car into her married lover after an argument, killing him. She was charged with murder, but was placed on probation because it was argued in court that her actions were related to severe PMS.
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Infradrian rhythm- deterministic?
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With things like the menstrual cycle and PMS, it says that biological rhythms may be beyond our control as seen with the study above. This means that people cannot be held responsible for their actions, and therefore this means that people could commit a crime and blame it on severe PMS.
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Reinberg- Infradrian rhythm?
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Reported on a woman who spent three months in a cave without natural lighting. Her menstrual cycle shortened to 25.7 days, implying that infradrian rhythms are influence by exogenous zeitgebers.
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Reinberg- IR- Eval?
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Not generalizable as it was just one women and therefore is unique, as there may be individual differences between women.
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Van cauter- life span changes?
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Examined several sleep studies involving male participants. Sleep was found to decrease during two life periods: between the ages of 16-25 years and 35 to 50 years.
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Floyd et al - life span changes?
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Reviewed 400 sleep studies, finding that REM sleep decreased by about 0.6 per cent a decade. The proportion of REM sleep increases from about age 70, though this may be due to overall sleep duration declining.
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Eaton- Evans and Dugdale- life span changes?
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Found that the number of sleep periods for a baby decreases until about 6 month of age, then increases until 9 months of age, before slowly decreasing again. This may be due to teething problems.
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Why do boys sleep more- evolutionary explanation?
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An evolutionary explanation for boys sleeping more is that they have more slow wave sleep, where growth hormones are released and this is so they are bigger and stronger, as they need muscle growth, to be better protectors.
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Parasomnias occurring in childhood?
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They are more common here than any other life stage. This includes night terrors. Sleepwalking is also more common because of the greater amount of SWS in which these Parasomnias occur.
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