Circadian Rhythms - researchers

Question 1

Siffre

Answer 1

• self styled caveman - spent extended period underground studying the effects of his biological rhythms
• deprived of natural light and noises
• he resurfaced after 2 months in 1962 then a decade later he did this again for 6 months

-in both cases, his ‘free running’ biological rhythms settled down to one.

• just beyond usual 24 hours -around 25 - but he did continue to fall asleep and wake on a regular schedule

Question 2

Aschoff and Wever

Answer 2

• similar results to siffre
• convinced participants to spend 4 weeks in ww2 bunker - no natural light
• all but one of the participants (their sleep wake cycle extended to 29 hours) displayed between 24 and 25 hours
• siffre’s experience and the bunker study suggest that the ‘natural’ sleep/wake cycle may be slightly longer than 24 hours but is entrianed by exogenous zeitgebers (number of daylight hours/ meal times)
• this shows the influence of exogneous zeitgebers on our internal bioloigcal clock is powerful

Question 3

Folkard

Answer 3

studied a group of 12 participants they lived in a dark cave for three weeks

• they were told to go to bed when the clock says 11:45 and rise when it said 7:45.

over the course of the study, the researchers gradually sped up the clock and so a 24 hour day lasted only 22 hours

• only one of the participants was able to comfortably adjust to the new regime

suggests the existence of strong free running circadian rhythms which can’t be easily overridden by exogenous zeitgebers

Question 4

Boivin

Answer 4

Boivin found that night workers engaged in shift work experience a period of reduced concentration around 6 in the morning (a circadian trough) - mistakes and accidents are mor likely

Question 5

Knutsson

Answer 5

Knutsson found that research pointed to a relationship between shift work and poor health .

shift workers are more likely to develop heart disease than those who have typical work patterns

Question 6

Solomon

Answer 6

Solomon concluded that high divorce rates in shift work might be due to the strain of deprived sleep and other influences such as missing out importnant family events

Question 7

Bonten

Answer 7

These rise and fall during the day which has led to the field of chronotherapeutic - how medical treatment can be administered in a way that corresponds to a person’s biological rhythms

E.g. aspirin reduces blood platelet activity and this can reduce the risk of heart attack,
Heart attacks are most likely to occur early in the morning, so the timing of taking aspirin matterns

Research has supported this (Bonten). This shows that circadian rhythm research can help increase the effectiveness of drug treatments.

Question 8

Czeisler

Answer 8

Czeisler found individual differences in sleep/ wake cycles varying from 13 to 65 hours.

Question 9

Folkard et al (1977)

Answer 9

Folkard demonstrated how children who had stories read to them at 3pm showed superior recall and comprehensions after a week compared to children who heard the same stories at 9am

Question 10

Gupta (1991)

Answer 10

Gupta found improved performance on IQ tests when participants were assessed at 7pm as opposed to 2 pm and 9 am