Ultradian Rhythms

• Ultradian Rhythms:


  • It Takes less than 24 hours to complete and usually occurs more than once a day (more than one cycle in 24 hours)
  • E.g. Stages of Sleep cycle (sleep stages cycle)
  • (i.e. more than once cycle in 24 hours - ultra diem meaning ‘beyond’ a day).
• Example of an Ultradian Rhythm?


  • The most well known ultradian rhythm is the sleep stages cycle.
  • Each cycle usually lasts around 90 minutes and goes through 5 stages
  • Each stage has different characteristics including brain wave patterns (each characterised by a different level of brainwave activity (monitored using EEG)).
• Stages of Sleep?


  • 5 stages of sleep have been identified:
  • Stage 1
  • Stage 2
  • Stage 3
  • Stage 4
  • above are all part of the Non REM (NREM)
  • Stage 5 = REM Sleep
• Stage 1 - overview?

  • Stage 1 of the 'sleep escalator' as the cycle is sometimes known are LIGHT SLEEP where person is easily woken
  • At the beginning of sleep the brainwave patterns start to become slower and more rhythmic (ALPHA WAVES - brain waves are high frequency and have a short amplitude)
  • 5% total sleeping time
• Stage 1 Characteristics?


  • Dreaming here is rare
  • Brain slowing down 
  • Eyes move slowly
  • Sometimes sudden muscle contractions occur (leading to falling sensation).
  • Breathing more regular 
  • Heart rate slows
  • Hypnagogic hallucinations
• Stage 2 overview?

  • Stage 2 of the 'sleep escalator' are also LIGHT SLEEP where person is easily woken
  • Here the alpha brainwaves become even slower (than in stage 1) as sleep becomes deeper (Theta Waves). There are also occasional random changes in pattern called sleep spindles.
  • 45-50% of total sleeping time
• Stage 2 Characteristics?


  • Synaptic pruning occurs here
  • Eye movement stops
  • Consciousness awareness of the outside world fades completely.
  • Lay down memories.
• Stage 3 overview & characteristics?


  • This is called deep sleep or slow wave sleep (SWS).
  • Involve delta waves, which are slower still and have higher amplitude and lower frequency  than earlier wave patterns.
  • It is difficult to wake someone at this point - Sleeper cut off from world completely
  • Deep sleep lasts longer in the first 2 cycles than in later cycles.
  • Some dreaming not as vivid as REM
  • 15-20% total sleep time
• Stage 4 overview?


  • This stage when you experience deepest sleep of the night, difficult to wake someone up 
  • 5-10%
  • This is known as deep sleep or slow wave sleep (SWS) Involve delta waves, which are slower still and have higher amplitude and lower frequency  than earlier wave patterns. It is difficult to wake someone at this point
• REM Sleep overview?


  • The body is paralysed yet brain activity speeds up significantly in a manner that closely resembles that of the awake brain. 
  • During this time, the brain produces theta waves and the eyes occasionally move around, thus rapid eye movement (REM). 
  • 20-25% of total sleep time here.
• REM Sleep Characteristics?


  • Rapid, shallow breathing, eyes jerk.
  • Temporary limb paralysis
  • Heart rate increases 
  • Blood pressure increases
  • Males get erections 
  • REM = ‘rapid eye movement’ - to denote the fast, jerky activity of the yes under the eyelids at this point.
  • Temperature irregular 
  • Here most dreams occur if woken here we are able to recall these dreams - if go back into cycle unlikely we shall be able to.
  • Research suggests that REM activity during sleep is highly correlated with the experience of dreaming - but may also occur in deep sleep.
• Stages of sleep?

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  A) ?