Ultradian rhythms

• What is an Ultradian rhythm

  A ultradiun rhythm is a rhythm which takes less than 24 houts to complete, therefore we will get more than one cycle in a day
• What is an example of a Ultradian rhythm

  The sleep cycle
• What is stage 1 in the sleep cycle

  Light sleep described as transitional, the body begins to relax and muscle activity slows down
• What is stage 2 in the sleep cycle

  Sleep begins to deepen, breathing rate slows and heart rate slows as the body further relaxes the brain is still relatively active
• What is stage 3 in the sleep cycle

  This stage moves into deep sleep, the brain activity moves to delta waves, a person would be difficult to wake up at this point
• What is stage 4 in the sleep cycle

  Very deep sleep the body shows evidence of repairing itself in this stage, the brain activity is slow muscles are inactive
• WHat is REM sleep

  Described as active sleep this is where dreaming occurs EEG recording at this time resemble an awake brain. The body is completely paralysed
• Key research which supports ultradian rhythms

  • REM sleep was first discovered by Aserinsky and Kleitman (1953) and Dement and Kleitman (1957) through the use of EEG which allowed them to learn that there were periods of sleep where the brain appeared to be active. During REM the brains activity resembles an awake brain and the eyes appear to move

  • Aserinsky and Kleitman (1953) and Dement and Kleitman (1957) also carried out research where they woke sleepers at various points during sleep and found that when people were woken during REM sleep 80% would report dreaming
• Strengths of the Research into ultraradian rhythm

  • Replications of Kleitman and Dement's (1957) study have consistently supported the existence of distinct sleep cycles behaving as ultradian rhythms

  • Research into sleep cycles has been used to help explain some of declines of old age. Cauter et al (2000) believes that reduced alertness in old age may be the result of their lower levels of slow wave sleep. This type of sleep is believed to decrease due to a reduced need for growth hormone which is only produces during slow wave sleep. This is a strength because it helps us understand differences in sleep
• Weakness of research into Ultraradium sleep

  This research takes a biological approach to sleep stages and life span stages suggesting that its only biology that should be taken into account. There are cultural and lifestyle factors that should be considered in sleep as well. Tynjala et al (1993) surveyed 11-16 year olds in 11 European countries and found the Iseaelis slept least and sweeds slept most. This suggests that the country you live in could affect the nature of your sleep
• Weakness of research into Ultraradium sleep

  Dement and Kleitman's research is criticised for a small sample size this is a problem because it is less generalisable because the sample wont reflect the whole population as a result causing a bias to certain people