Circadian rhythm Flashcards
What are biological rhythms?
Distinct patterns of changes in body activity that conform to cyclical time periods
What are circadian rhythms?
Biological rhythms subject to a 24-hour cycle
What are examples of a circadian rhythm?
Sleep/wake cycle and core body temperature
What are endogenous pacemakers?
The body’s internal biological clock
What are exogenous zeitgebers?
External factors in the environment that entertain our biological rhythms
What is the case of Michel Siffre?
He spent 2 months in the southern Alps and 6 months in Texan caves deprived of natural light and found his sleep/wake cycle just beyond 24h to a 25h sleep/wake cycle
What was Aschoff and Wever’s experiment?
Participants spend 4 weeks in WW2 bunkers deprived of natural light but with access to food and drink.
What were Aschoff and Wever’s findings?
39/40 participants sleep/wake cycle was 24-25 hours (one cycle went to 29h)
What were Aschoff and Wever’s conclusions?
Natural sleep/wake cycle is slightly longer than 2h but is entrained by exogenous zeitgebers associated with the 24h day
What was Folkard’s study?
12 participants lived in a dark cave for 3 weeks and went to bed at 11:45pm then rose at 7:45am, but researchers gradually sped up the time so the day only lasted 22h
What were Folkard’s findings?
Only 1 participant could adjust to the 22h day so the strong circadian rhythm cannot be easily run over exogenous zeitgebers
What are methodological issues with research into circadian rhythms?
Very small sample size as few participants and poor control and light is too bright so could impact sleep/wake cycle.
What are issues with individual differences for circadian rhythms?
All the samples are very small so sleep/wake cycles may differ widely
What is research evidence for individual differences?
Czeisler and Duffy
What did Czeisler find?
Research found individual differences from 13h to 65h
