Circadian rhythms

Question 1

what are biological rhythms?

Answer 1

• patterns of change in activity governed by body’s bio clock (endogenous pacemakers) and external changes to environment (exogenous Zeitgebers)

Question 2

what is a circadian rhythm?

Answer 2

• some occur through the day (ultradian) like sleep/wake

- some take longer than a day (infradian) like menstrual

Question 3

how is body temperature affect by circadian rhythm?

Answer 3

• lowest at 4am (36 degrees) - highest at 6pm (38 degrees)

- high body temperature makes us more cognitively able

Question 4

+ what studies were done to support body circadian rhythm influencing body temperature?

Answer 4

• Folkard 7(7) found kids who read stories at 3pm had better recall after a week compared to those reading at 9pm
• Gupta (91) improved IQ tests when assessed at 7pm rather than 2pm or 9am

(doesn’t account for individual difference or independent groups)

Question 5

how is the sleep wake cycle influenced by circadian rhythms?

Answer 5

sleepiness during night caused by exogenous Zeitgebers (lack of sunlight) as it causes production of melatonin which shuts down body

Question 6

+ what was Siffre’s study into the sleep/wake cycle on circadian rhythms?

Answer 6

• spent long periods underground deprived of natural light (told when to eat and drink)
• emerged 2 months later thinking it had only been a month
• redid study 10 years later for 6 months with free running bio clock (still around 24-25hrs)

Question 7

+ supporting study of sleep wake cycle

Answer 7

• Ashcoff and Wever (76) sent people into ww2 bunker with no light for 4 weeks
• all but one persons rhythm was between 34 and 35 hrs
• still about 24hrs even with free running bio-clock (no zeitgebers)