ultradian

• what are ultradian rhythms? 


  biological rhythms that span less than 24 hours
• what is an example of ultradian rhythms? 


  sleep cycle
• how long is a sleep cycle? 


  60 minutes in infancy up to 90 minutes
• what is stage 1 of NREM sleep? 


  transition from wakefulness to sleep; theta waves; hyponogogic state (hallucinations)
• what is stage 2 of NREM sleep? 


  first point of true sleep; theta waves interrupted by sleep spindles and K-complexes
• what are sleep spindles? 


  short bursts of brain activity
• what are K-complexes? 


  responses to external stimuli
• stage 3 of NREM sleep? 


  long, slow delta waves with fewer sleep spindles. heart, breathing and metabolic rate all slow down
• stage 4 of NREM sleep? 


  slow wave sleep; long slow delta waves; body temp, heart rate and blood pressure drop to lowest point and growth hormones are secreted; sleep walking/talking and night terrors may also occur
• REM sleep


  rapid eye movement; beta waves associated with being awake; AKA "paradoxical sleep" because body is still completely paralysed; when dreaming occurs
• how many sleep cycles occur a night? 


  5 on average
• how do sleep stages change across a sleep staircase?

  SWS period gets shorter and REM period gets longer as night progresses
• what are electro-oculograms (EOGs)?


  measures eye movement
• what are electromyograms (EMG)?


  measures muscle movement
• findings from Friedman and Fisher:


  basic rest activity cycle of eating and drinking behaviour every 90 minutes in psychiatric patients
• supporting evidence for BRAC: Bollani


  babies showed shallow ultradian temperature fluctuations more than once a day; demonstrates 90 minute cycle outside of sleep
• findings from Empson


  in partial sleep deprivation study, participants spent more time in REM sleep when deprived of it the night before; shows REM rebound effect and sleep's endogenous nature
• what 2 processes of firing neurotransmitters have been found to control sleep stages?

  Pons fires ACh before REM sleep

  raphe nucleus (produces serotonin) and locus coerulus (produces noradrenaline) are involved in NREM sleep, inhibits ACh production
• findings from jasper and tessier


  ACh was highest and serotonin and noradrenaline was lowest in cat cortex during REM sleep
• findings from stoyva and metcalf 


  when exposed to incesticides (increases ACh) they spend longer in REM, shows human evidence for role of neurotransmitters in regulating ultradian stages of sleep