Ultradian rhythms

• When do ultradian rhythms occur?


  More than once every 24 hours
• What is an example of an ultradian rhythm/

  Stages of sleep
• How many stages of sleep are there?

  five
• What is each stage of sleep categorised by?

  A different level of brainwave activity
• What are stages 1 and 2 of sleep called?

  Light sleep
• What happens in stage 1 & 2 of sleep?

  Person can be easily awoken, brainwaves become slower and more rhythmic, alpha waves progress to theta waves
• What are stages 3 & 4 of sleep called?

  Deep sleep
• What happens in stage 3 and 4 of sleep?

  Slow wave sleep stage. Difficult to wake someone up.
• What waves is stage 3&4 of sleep associated with?

  Delta waves
• What is stage 5 of sleep?


  REM sleep
• What happens in REM sleep?

  (Rapid eye movement), the body is paralysed and brain activity resembles that of an awake person
• How long is each sleep cycle?

  90 minutes
• how many sleep cycles per night?

  4-5 cycles
• What is a strength of ultradian rhythms? (Understanding of age-related changes in sleep)

  P) Ultradian research has led to an improved understanding of age-related changes in sleep.

  
  

  E) Sleep scientists have identified that deep sleep (slow wave sleep) reduces with age. According to cauter et al (2000) this may explain various issues in old age, such as reduced alertness.

  
  

  T) Therefore in order to increase deep sleep (SWS) relaxation and medication may be used, this suggests that research findings into ultradian rhythms has practical value.
• What is a weakness of ultradian rhythms? (Lack of ecological validity)


  P) The way in which such research is conducted may tell us little about ultradian rhythms in humans.

  
  

  E) When investigating sleep patterns, participants must be subjected to a specific level of control and be attached to monitors that measure such rhythms. This may be invasive for the participant, leading them to sleep in a way that does not represent their ordinary sleep cycle.

  
  

  T) This makes investigating ultradian rhythms, such as the sleep cycle, extremely difficult as their lack of ecological validity could lead to false conclusions being drawn.
• What is a strength of conducting studies in a lab environment?

  Can control extraneous variables and replicate studies to check for consistency.
• What is another strength of ultraradian rhythms? (Case studies- flexibility)


  P) Case studies indicates the flexibility of ultradian rhythms.

  
  

  E) Randy Gardener remained awake for 264 hours. While he experienced numerous problems such as blurred vision and disorganised speech, he coped rather well with the massive sleep loss. After this experience, Randy slept for just 15 hours and over several nights he recovered only 25% of his lost sleep. Interestingly, he recovered 70% of Stage 4 sleep, 50% of his REM sleep, and very little of the other stages.

  
  

  T ) These results highlight the large degree of flexibility in terms of the different stages within the sleep cycle and the variable nature of this ultradian rhythm.