ultradian rhythms

Ultradian rhythms - the sleep cycle

A type of overtrading rhythm is the stages of sleep - the sleep cycle. Psychologists have identified five distinct stages of sleep that can altogether last for approximately 90 minutes., the cycle repeats throughout night. They characterised by a different level of brainwave activity.

Stages of sleep

• Stages 1 and 2 - this is known as light sleep where a person may be easily woken. In stage 1, alpha waves are high frequency and amplitude. In stage 2 alpha waves but there are occasional random changes called sleep spindles.

• Stages 3 and 4 - this is known as deep sleep of slow wave sleep (SWS) where it is difficult to be woken up. There are Delta waves with lower frequency and high amplitude.

• Stage 5 (REM sleep) - the body is paralysed yet the brain closely resembles that of the awake brain. The brain produces theta waves and eyes occasionally move around : rapid eye movement (REM). Dreams are often experienced during REM sleep.

Strength

• One strength is that it has improved the understanding of age related changes in sleep - scientists have observed that SWS reduces with age. Growth hormone is mostly produced during SWS therefore it has reduced in older people. According to Eve Van Cauler (2000), the resulting asleep deficit may explain various issues and old age such as reduced alertness

Limitation

• One limitation of Ultradian rhythms is that there is significant variation between people - Tucker (2007) found large differences between participants in terms of the duration of each stage stage, particularly 3 and 4. Tucker suggested that these differences are likely to be biologically determined, making it difficult to describe normal sleep