Ultradian Rhythms

Question 1

What is an ultradian rhythm?

Answer 1

Cycles that last less than 24 hours

Question 2

Outline the stages of sleep

Answer 2

Sleep stages occur in 90 minute periods. Divided into 5 stages, each stage is characterised by different level of brain brain wave activity

Question 3

Describe the different stages of sleep

Answer 3

• Awake: waves are close together and short beta waves
• Stage 1: Brain waves slow down, regular, greater amplitude alpha waves
• Stage 2: Waves have lower frequency, theta waves. Accompanied by bursts of activity
• Stage 3 and 4: Slower delta waves (slow wave sleep). When most of the body’s ‘repair work’ is done
• REM sleep (rapid-eye movement): Eyes and brain are activated but body is paralysed. Combination of wave types. Correlated with dreaming

Question 4

Describe the basic rest activity

Answer 4

• Kleitman suggests the BRAC is characterised by continuing during the day aswell, even when awake. Rather than moving through sleep stages, in the day we move from alertness to physiological fatigue every 90 minutes.
• Research suggests the human mind can focus for about 90 mins, towards the end, the body loses concentration, fatigue and hunger.
• BRAC in wakefulness isn’t as obvious in sleep, but everyday evidence like 10:30 coffee break allows workers to divide 9am to noon

Question 5

Give evidence for the basic rest activity cycle

Answer 5

Ericsson et al studied a group of elite violinists and found practice sessions were limited to 90 mins, with practice systemically disturbed during the day in 90 mins segments. Violinists napped to recover.
- There’s also evidence of the BRAC for athletes

Question 6

Give evaluation for ultradian rhythms (improved understanding)

Answer 6

• A strength of ultradian rhythms research is that it’s improved understanding of age-related changes in sleep
• SWS has been observed to reduce with age. Growth hormones are mainly produced in SWS so this is reduced in older people. Eve van Cauter argues, the resulting sleep deficit may explain some issues in old age, e.g. reduced alternes. Relaxation and medication may increases SWS
• Suggests knowledge of ultradian rhythms has practical value

Question 7

Give evaluation for ultradian rhythms (individual differences)

Answer 7

• One limitation of ultradian rhythms is individual differences in sleep stages.
• Tucker et al found large differences between participants in terms of the duration of stage 3 and 4 of sleep. They suggest these differences are biologically determined
• This makes it difficult to discuss ‘normal sleep’ in any meaningful way