ultradian rhythms

• ultradian rhythms are biological rhythm that happens more than once in a 24 hour period.
• example: sleep stages:

  -5 stages of sleep, go in a cycle and happen more than once in 24 hours

  -measured brain activity using EEG

  -stages 1 & 2: 'sleep escalator' - light sleep, easy to wake up: 5-15mins

  -stages 3 & 4: deep sleep, hard to wake up: 5-15mins

  -(stage 5) REM sleep: body is paralysed but brain activity mirrors that of the waking brain: 20 mins
• Dement & Kleitman:

  -9 ppts (7M, 2F)

  -documented what happens in REM

  -EEG, sleep lab

  -had no caffeinated drinks the day before

  -all ppts had REM sleep and were woken up during this, asked if they were dreaming & most said yes & said what the dreams were

  -sensors were put on eyelids: eyelid movement matched that of the dream described

  -all people go through the stages more than once in 24 hours
• Strengths:

  -Dement & Kleitman. Repeat the sleep cycles within 24 hours. D: little ext. val: lab. Supports UR BUT small sample.

  -RWA: Van Cauter et al (2000): changes in sleep patters & little deep sleep is linked to old people - applied to medications to increase deeper sleep. Economic implications: deep sleep = better performing at work = more money to economy.

  Weakness:

  -more tolerant to change than CR. CS: R. Gardener didn't sleep for 264h but he coped. Only caught up on stage 4 sleep. D: case study lacks representation. UR are less important as they are easy to override.