Ultradian Rhythms

• Ultradian rhythms - sleep cycle explained

  -Sleep cycle takes less than 24 hours to complete a full cycle ... it repeats numerous times within a 24h period.

  -Each cycle lasts approx 90 mins. Most people will go through 5 cycles during one full sleep session.

  -The sleep cycle is characterised by the cyclical pattern of entering and leaving the non-rem and rem stages.

  - Each stage is characterised by the brainwave patterns which repeat in a fixed rhythmic duration.
• Ultradian rhythms - sleep cycle explained

  -There are 4 key stages of sleep. One full cycle consists of entering non-rem stages and descending into deep sleep. Stages 1-4 then ascending through stages 3 and 2. Exit the non-rem and then enter the rem stage.

  -This cycle repeats every 90 mins, REM sleep increases and deep non-rem sleep decreases.
• Individual differences


  -Research has found that new-borns spend around 50% of sleep in the REM stage, compared to 25% in adults.

  -This shows how ultradian rhythms change throughout an individuals life span and in response to the developmental needs of the person.
• Research into ultradian rhythms

  -Investigated the differences in REM and non-REM stages of sleep.

  -While sleeping an EEG recorded changes in brain wave patterns.

  -Awoke during REM and non-REM stages and asked to report if they had a dream and if so how long.

  -mean REM cycle lasts 20 minutes.

  -Mean sleep cycle duration lasted one sleep cycle lasted 90 mins (consisting of REM and non-REM).

  -Concluded that sleep involves a fixed, repetitive cycle in and out of REM and non-REM. REM sleep is associated with dreaming.