Studied by 0 people
Looks like no one added any tags here yet for you.
Biological rhythms
Distinct patterns of changes in body activity that conform to cyclical time periods.
Circadian rhythms
A 24 hour cycle (such as sleep-wake cycle and changes in core body temperature).
Supporting Research: Siffre
Isolated from external factors (light as he stayed underground)
maintained a regular sleep-wake cycle but it lasted longer than 24 hours
sleep-wake cycle caused by internal factors but external factors are necessary to fit it to the day/night cycle.
Supporting research: Aschoff and Wever
participants spent 4 weeks in WW2 bunker, no natural light (isolated from external factors)
they maintained a regular sleep-wake cycle but it lasted longer than 24 hours except for one participant.
sleep-wake cycle caused by internal factors but external factors are necessary to fit it to the day/night cycle.
Supporting research: Folkard et al
12 people in a cave for 3 weeks
Researchers sped up the clock so a day lasted 22 hours.
one participant was able to adjust, clocks as external factors have little impact, therefore supporting internal factors.
Supporting research: Czeisler
found it's better to change shifts less often (every 21 days rather than 7)
found it's better to rotate with the clock than against it (staying up later when adjusting to the new shift, get less sleep than more)
Practical applications: Night shift workers
accidents/mistakes more common during circadian trough (6am)
health consequences for shift workers
+Supports internal factors due to negative consequences when external factors try to override internal.
+suggests circadian rhythms are caused by internal factors
Individual differences:
free-running sleep-wake cycles can range from 13 to 65 hours
cycles may change with age (siffre's later cave studies showed a slower circadian rhythm than his earlier ones)
most individuals are affected by similar external factors but maintain individual regular internal rhythm
