Biological Rhythms

Front 1

Disruption of biological rhythms

Back 1

Endogenous pacemakers become desynchronised with exogenous zeitgebers. Shift work & jet lag are examples of this

Hint 1

Desynchronisation of exogenous and endogenous

Front 2

Shift work

Back 2

Breakdowns in the relationship between internal body clocks (SCN) and external cues (light). At night, when body temperature and metabolism are lower and there is no natural light, it's harder to sleep because metabolism and light levels are higher.

Hint 2

Body temperature, metabolism

Front 3

Shift work - phase advance & phase delay

Back 3

Worst when working hours are changed more frequently and more drastically. ( going from 10pm shift to a 9am shift), as there is no time to adjust. Research also shows that changing shifts forward in time (phase advance) causes less disruption than pushing shifts back in time (phase delay), it's easier to move from a 6am to a 4am shift than the other way round.

Hint 3

Phase advance causes less disruption than phase delay

Front 4

Effects of shift work

Back 4

Disruption of biological rhythms can cause severe stress, leading to greater problems such as increased risk of heart disease, sleep. Ineffective shift rotation can be damaging for employers as well, as productivity and concentration may be lower during night shifts. In extreme cases, tiredness can have disastrous consequences e.g. Chernobyl disaster, explosion lead to radioactive gases spreading all around the surrounding regions of a nuclear power plant. This occurred at night, could be due to the shift workers' lack of concentration.

Hint 4

Health problems, low productivity, Chernobyl disaster

Front 5

Czeisler et al

Back 5

Studied shift-workers at a factory in Utah, finding that they had high illness rates, sleep disorders and elevated stress. When he persuaded management to move to a phase delay system, and adjust shifts every 3 weeks, workers appeared healthier and output was up. Can't generalise findings, only one factory.

Hint 5

Supports,Utah, phase delay system

Front 6

Colligan et al

Back 6

Found that workers with shift rotations had more accidents than workers on set shift, and also drank more and had less successful social relationships, demonstrating the damage of shift work in disrupting biorhythms.

Hint 6

Supports, accidents, drink

Front 7

Moor Ede

Back 7

Highlighted the consequences that can come from shift work, finding that decreased alertness as a result of shift lag costs the USA $70 billion per year.

Hint 7

Support, USA, loss of profit

Front 8

Practical applications

Back 8

Employers can change shift patterns to make them less damaging in the ways that the research has indicated.

Hint 8

Supports, employers can make changes

Front 9

Nomothetic

Back 9

In suggesting general rules for what makes shift work easier to cope with; by not taking account of individual differences, research in the area is reductionist. Some people may be better able to reset their sleep/wake cycle than others

Hint 9

Against, reductionist, individual differences.

Front 10

Jet lag

Back 10

Caused by travelling across time zones so quickly that biological rhythms do not match external cues, causing sleepiness during the day and restlessness at night. This lasts until desynchronisation occurs, best achieved by being allowed to follow exogenous zeitgebers (light) in the new time zone.

Hint 10

Biological rhythms don't match external cues, follow exogenous zeitgebers

Front 11

Jet lag - travellingsympto

Back 11

Worse travelling from west to east than it is travelling east to west. This is because you are ahead of local time, so the day is lengthened and by the time night comes, you are already exhausted and ready for bed, as opposed to having to force yourself to sleep when the day is shortened.

Hint 11

Worse west to east

Front 12

Symptoms of jet lag

Back 12

Fatigue, irritability, confusion, irregular bowel movements

Front 13

Recht et al

Back 13

Studied a US basketball team, finding that when they travelled east they won only 37% of their games, but won 44% when they travelled west, highlighting the effects of jet lag on performance and providing evidence for phase delay being less harmful in jet lag. Cultural bias, extraneous variables (drinking) could have affected performance, arguable whether it's a significant difference.

Hint 13

Support, US basketball team, phase delay