2.0 STAGES OF SLEEP
2.1 Non-Rapid Eye Movement (NREM) Sleep
Non-rapid eye movement (NREM) sleep can be characterized into three distinct stages, previously classified into four stages. NREM sleep can be differentiated from rapid eye movement (REM) sleep due to its lack of muscle paralysis and bursts of eye movement typically observed in REM sleep3. Additionally, NREM sleep demonstrates characteristic waves and spindles captured on electroencephalogram (EEG) readings that differ significantly from REM sleep5.
2.1.1 Stage 1 NREM Sleep
During periods of wakefulness, a frequency of greater than 13 Hz can be read on an EEG output, which is frequently denoted as a beta wave. However, as an individual approaches sleep onset, a change in the EEG reading can be observed6. Stage 1, otherwise known as N1 sleep, follows a low voltage frequency wave pattern of 2 to 7 Hz, often denoted by theta waves. Not surprisingly, muscle tone is maintained and slow eye movements may be observed. Because the stages of sleep follow a cycle, N1 sleep may last for 1 to 7 minutes 3, 7. It is important to note that individuals can be wakened more effortlessly in this state due to a lower arousal threshold3.
2.1.2 Stage 2 NREM Sleep
Following N1 sleep, stage 2 (N2) sleep …show more content…
In the first sleep cycle, REM sleep lasts approximately 1 to 5 minutes before a new sleep cycle begins3. A change in EEG activity is observed upon the onset of the REM stage. Additionally, muscle atonia prevents movement of the individual, apart from diaphragmatic activity and episodes of rapid eye movements3, 6. REM sleep corresponds to the dreaming stage of sleep and it is often called paradoxical sleep because based exclusively on the EEG readings, it would appear that the individual is awake. However, due to the relative muscle paralysis, an individual is in an unresponsive
2.1 Non-Rapid Eye Movement (NREM) Sleep
Non-rapid eye movement (NREM) sleep can be characterized into three distinct stages, previously classified into four stages. NREM sleep can be differentiated from rapid eye movement (REM) sleep due to its lack of muscle paralysis and bursts of eye movement typically observed in REM sleep3. Additionally, NREM sleep demonstrates characteristic waves and spindles captured on electroencephalogram (EEG) readings that differ significantly from REM sleep5.
2.1.1 Stage 1 NREM Sleep
During periods of wakefulness, a frequency of greater than 13 Hz can be read on an EEG output, which is frequently denoted as a beta wave. However, as an individual approaches sleep onset, a change in the EEG reading can be observed6. Stage 1, otherwise known as N1 sleep, follows a low voltage frequency wave pattern of 2 to 7 Hz, often denoted by theta waves. Not surprisingly, muscle tone is maintained and slow eye movements may be observed. Because the stages of sleep follow a cycle, N1 sleep may last for 1 to 7 minutes 3, 7. It is important to note that individuals can be wakened more effortlessly in this state due to a lower arousal threshold3.
2.1.2 Stage 2 NREM Sleep
Following N1 sleep, stage 2 (N2) sleep …show more content…
In the first sleep cycle, REM sleep lasts approximately 1 to 5 minutes before a new sleep cycle begins3. A change in EEG activity is observed upon the onset of the REM stage. Additionally, muscle atonia prevents movement of the individual, apart from diaphragmatic activity and episodes of rapid eye movements3, 6. REM sleep corresponds to the dreaming stage of sleep and it is often called paradoxical sleep because based exclusively on the EEG readings, it would appear that the individual is awake. However, due to the relative muscle paralysis, an individual is in an unresponsive