ultradian rhythms

• an ultradian rhythm is a biological rhythm which repeats more frequently than once every 24 hours
• an example of an ultradian rhythm is the sleep cycle and meal patterns
• there are 5 stages of sleep
• stages 1 + 2: light sleep, alpha waves which change in pattern in stage 2 (sleep spindles and k-complexes)
• a k-complex is a large wave that often occurs in response to environmental stimuli
• stages 3 + 4: deep sleep / slow wave sleep (SWS) - difficult to wake

  delta waves
• stage 5: REM sleep - body is paralysed yet brain is active, dreams are experienced here

  theta waves are produced
• REM means rapid eye movement
• NREM means non-rapid movement
• BRAC: basic rest-activity cycle which is characterised by a period of alertness followed by physiological fatigue
• randy gardener was awake for 264 hours and experienced blurred vision and disorganised speech due to his lack of sleep

  he slept for 15 hours afterwards and recovered 25% of his sleep, 50% of his REM sleep, and 70% of stage 4
• AO3: tucker et al - found large differences between participants in the duration of each sleep stage (particularly between stages 3 and 4)

  this suggests that there may be innate biological differences in ultradian rhythms

  this study was carried out in a lab, meaning that situational factors did not impact the findings, suggesting that there are only biological differences here
• AO3: ultradian rhythms have improved our understanding of age-related changes in sleep

  SWS reduces with age as a growth hormone is produced during SWS