Ultradian rhythms and sleep cycles

Question 1

Ultradian rhythms+example

Answer 1

-Ultradian rhythms are biological rhythms that occur multiple times in a 24 hour period
-For example the sleep cycle, which has 5 distinct stages, that are characterised by distinct characteristics

Question 2

Stage 1 of the sleep cycle

Answer 2

-In stage 1 (light sleep) the individual is easy to wake, and their body can move randomly (hypnic jerks)
-EEGs show alpha/theta waves

Question 3

Stage 2 of the sleep cycle

Answer 3

-In stage 2 of the sleep cycle, the individual is harder to wake up and their body is more relaxed, with their heart rate and body temperature lowering during this stage
-EEGs show slow theta waves

Question 4

Stage 3 of the sleep cycle (deep sleep)

Answer 4

-Stage 3 of the sleep cycle is the deepest sleep; the body is the most relaxed and the heart rate is the lowest
-EEGs show delta waves, but there can be occasional spikes in activities called sleep spindles and k complexes

Question 5

Stage 4 of the cycle

Answer 5

-Stage 4 of the sleep cycle is REM; this involves the body being paralysed, but experiencing random eye movements, and is associated with dreams, as participants woken up report the most vivid dreams during this stage
-EEGs show theta waves

Question 6

Stage 5 of the cycle

Answer 6

-In stage 5 of the sleep cycle, it returns to stage 1 (light sleep)
-This cycle can repeat up to five times in one night

Question 7

Research evaluation for sleep cycles (Dermot and Klietman 1957)

Answer 7

-Dermot and Klietman (1957) Brain activity in 33 participants was measured using EEG scans during a night’s sleep
-It was found that there was a cyclic activation cycle, with body relaxation during slow-wave sleep, and random eye movement occuring during intense periods of activation
-This provides support for the existence of the sleep cycles and ultradian rhythms