Biological rhythms: Circadian rhythms

Question 1

What are biological rhythms?

Answer 1

-Distinct patterns of changes in body activity that conform to cyclical time periods
-They are influenced by Endogenous pacemakers (internal body clocks) and external cues (exogenous zeitgebers)

Question 2

What are circadian rhythms?

Answer 2

-24hr cycle
-regulates body processes such as sleep wake cycle and body temperature.

Question 3

Describe Simon Folkard’s et al (1985) research into circadian rhythms?

Answer 3

-Studied a 12 people living in a cave for 3 weeks
-they went to bed when clock said 11:45 and rose when it said 7:45
-Over the course of the study, they gradually sped up the clock so 24 hr day only lasted 22 hours
-Only 1 participant was able to comfortably adjust to the new regime

Question 4

Describe Michel Siffre’s research into circadian rhythms?

Answer 4

-Spent 2 months in a cave without exposure to natural light but had a lamp ,food and drink
-Left the cave in mid- September 1962 and thought it was August
-Later spent 6 months in a cave in Texas
-When asked to count to 120, 1 digit per second, it took him 5 minutes
-His free running biological rhythm was beyond 24 hours and even got to a 48 hr rhythm

Question 5

Describe Aschoff and Wever’s (1976) research into Circadian rhythms

Answer 5

-convinced group of participants to spend 4 weeks in ww2 bunker without light
-All but one participant (whose cycle went to 29 hrs) displayed a circadian rhythm of 24-25 hours
-Both research shows how sleep/wake cycle is slightly longer than 24 hours but is entrained by exogenous zeitgebers.

Question 6

Strengths of circadian rhythms

Answer 6

-Shift work and consequences of desynchronisation:
Bolvin et al. (1996): Night workers engaged in shift work experience a period of reduced concentration in 6am meaning more mistakes are made.
Knutsson (2003): shift workers are 3x more likely to develop heart disease than people who work normal patterns.
HOWEVER: highly correlational research- Charlene Solomon (1993): concluded high divorce rates in shift workers is because of sleep deprivation.

-Medical Treatment: chronotherapeutics ( how medicine can be administered to correspond to a persons biological rhythms). Heart attacks are more frequent in the morning so it is best to take aspirins (which reduce chance of heart attack) last thing at night. Research by Bonten et al. (2015) supports this

-Real life application in shifting school day: Wolfson and Carskadon (1998) recommend school day start later to fit in with the natural teenage chronotype so they do not start school later. The Adolescent sleep working group (2014) found increased academic performances and less reliance on caffeine when the school day started later.
HOWEVER: inconvenience for teachers and parents and arguments that this would only encourage students to stay up later and still be tired.

Question 7

Weaknesses of research into circadian rhythms

Answer 7

-Small sample sizes in Michel Siffres research: case study so 1 participant so not generalisable

-Individual differences: Charles Czeizler et al. (1999) found individual differences in sleep/wake cycles varying from 13-65 hours. Jeanne duffy et al. (2001) revealed that some people have natural preference to sleeping early and waking early (larks) or the opposite (owls)