Circadian rhythms BP

Question 1

Circadian rhythms

Answer 1

biological rhythms subject to 24 hour cycle, which regulate a number of body processes such as the sleep/wake cycle and changes in the core body temperature

Question 2

Biological rhythms definition

Answer 2

distinct patterns of changes in body activity that conform to cyclical time periods. Biological rhythms are influenced by internal body clocks (endogenous pacemakers) as well as external changes to the environment (exogenous zeitgebers)

Question 3

chronotherapeutics

Answer 3

how medical treatment can be administered in a way that corresponds with biological rhythms

Question 4

Siffre

Answer 4

• spends multiple periods of extended time underground to measure the effects on his biological rhythms.
• After having no natural light or sound after one exhibition he resurfaced in mid-September believing it to be mid-august in the Southern Alps.
• The biological rhythm settled to 25 hours (normal is 24) and he continued to fall asleep and wake up on a regular schedule.

Question 5

Aschoff and Wever

Answer 5

• Convinced participants to spend 4 weeks in a WW2 bunker with no natural light
• Most participants displayed regular 24-25 hour circadian rhythms
• One participant experienced a sleep/wake cycle of 29 hours

Question 6

similarities between Siffre and Aschoff’s research

Answer 6

Both studies show that the ‘natural’ sleep/wake cycle may be just over 24 hours but it is entertained by exogenous zeitgebers associated with our 24 hour clock eg typical meal times

Question 7

Folkard et al displays evidence to show that we should not overestimate the influence of exogenous zeitgebers:

Answer 7

• Studied 12 people living in a dark cave for 3 weeks, retiring to bed when the clock said 11.45 and waking up at 7.45
• Gradually, researchers sped up the clock but did not tell the participants so the day was eventually only 22 hours
• Only 1 participant could comfortable adjust to the new regime
• This suggests the existence of a strong free-running circadian rhythm that cant be overridden by exogenous zeitgebers

Question 8

Boivin et al

Answer 8

found that night workers engaged in shift work experience a period of lack of concentration at about 6 in the morning, so mistakes more likely

Question 9

Boten et al

Answer 9

found the timing of taking aspirin (reducing blood platelet activity) important as heart attacks normally occur in the morning

Question 9

Knutsson

Answer 9

found that shift workers are 3 times more likely to develop heart disease that people working normal work patterns

Question 10

Solomon

Answer 10

found that high divorce rates in shift workers may be due to strain of deprived sleep and influences like missing out on family events

Question 11

Czeisler et al

Answer 11

ound individual differences varying from 13-65 hours

Question 12

Duffy et al

Answer 12

found some people like to go to bed early and wake up early (larks) but some do the opposite (owls)

Question 13

Wolfson and Carskadon

Answer 13

recommended that school should start a couple hours later to fit teenagers chronotype (sleep pattern). But shifting the day is disruptful to teachers and parents. It also limits the number of available after school activities

Question 14

I

Shift work

strength

Answer 14

Research provides understanding of the consequences that occur when circadian rhythms are disrupted (desynchronisation)

Question 15

D

Shift work

strength

Answer 15

Boivin and Knutsson’s research

Question 16

E

shift work

strength

Answer 16

Research into the sleep/wake cycle may have RW economic implications for how to best manage worker productivity.

Question 17

I

counterpoint to shiftwork

limitation

Answer 17

Studies investigating the effects of shift work often use correlational methods

Question 18

D

counterpoint to shiftwork

limitation

Answer 18

• Difficult to establish whether desynchronisation of sleep/wake cycle is actually a cause of negative effects
• May be other factors
• Solomon’s research

Question 19

E

counterpoint to shiftwork

limitation

Answer 19

Biological factors might not create the adverse consequences associated with shift work.

Question 20

I

medical treatment

strength

Answer 20

Research has been used to improve medical treatments

Circadian rhythms coordinate many of the bodies basic procedures like heart rate, which rise and fall during the day

Question 21

D

medical treatment

strength

Answer 21

• Lead to the field of chronotherapeutics (how medical treatment can be administered in a way that corresponds with biological rhythms)
• Boten et al’s research

Question 22

E

medical treatment

strength

Answer 22

Research can help increase the effectiveness of drug treatments.

Question 23

I

individual differences

limitation

Answer 23

Generalisations are difficult to make

Question 24

# D individual differences | limitation

Answer 24

* The work of Siffre, Aschoff and Wever are all based on very small samples * sleep/wake cycles can vary widely * Czeisler's research * Duffy's research

Question 25

# E individual differences | limitation

Answer 25

It is difficult to use the research data to discuss anything more than averages, which could be meaningless.

Question 26

biological rhythms

Answer 26

All are governed by 2 things: * Endogenous pacemakers (internal body clock) * Exogenous zeitgebers (environmental changes) Some rhythms occur during the day (ultradian rhythms) and others take longer than a day (infradian rhythms).

Question 27

the sleep/wake cycle

Answer 27

Daylight (an exogenous zeitgeber) has an effect on our sleep/wake cycle. But it is also controlled by an endogenous pacemaker called the suprachiasmatic nucleus SCN. This lies above the optic chiasm, which provides information from the eye about light. Light can reset the SCN.

Question 28

**Gupta**

Answer 28

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