Circadian rhythms

Question 1

What two things govern biological rhythms?

Answer 1

Exogenous zeitgeibers

Endogenous pacemakers

Question 2

What are exogenous zeitgeibers?

Answer 2

External changes in the environment

Question 3

What are endogenous pacemakers?

Answer 3

The body’s biological internal clock

Question 4

What is a circadian rhythm?

Answer 4

A rhythm that occurs that last within the 24 hour cycle

Question 5

What is an example of a circadian rhythm?

Answer 5

Sleeping

Question 6

What is daylight and what is the effect of it?

Answer 6

Exogenous Zeitgeiber

Causes people to feel awake during the day and drowsy at night time

Question 7

When is core body temperature at the lowest?

Answer 7

At around 4am

36 degrees

Question 8

When is core body temperature at the highest?

Answer 8

at around 6pm

38 degrees

Question 9

What does evidence suggest about the effect of body temperature?

Answer 9

It affects mental abilities, suggesting that the warmer we are the better our cognitive performance

Question 10

What did Folkard et al (1977) find?

Answer 10

Children who had stories read to them at 3pm had significantly better recall and comprehension after a week compared to children who heard the same story at 9am

Question 11

What did Gupta (1991) find?

Answer 11

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

Question 12

Outline Sieffre’s cave study (1962)?

Answer 12

He spent 2 months in a cave in July and resurfaced in mid September, believing it was mid August.
He was deprived of exposure to natural light and sound but had access to adequate food and drink

Question 13

What were the results of Sieffre’s cave study? (1962)

Answer 13

His free-running body clock settled at a little longer than the normal 24 hours.
He slept and woke at regular intervals.

Question 14

What conclusions can be drawn from Sieffre’s cave study (1962)?

Answer 14

We have a very strong internal body clock which is hard to deviate from

Question 15

What are some evaluative points for Sieffre’s study? (1962)

Answer 15

• He had poor control
• He carried it out again at age 60 but when you get older your internal body clock is slower anyways so age is then a confounding variable

Question 16

Outline Aschoff and Wever (1976)?

Answer 16

They had a group of participants spend 4 weeks in a WW2 bunker, deprived of natural light.

Question 17

What were the results for Aschoff and Wever’s study? (1976)

Answer 17

Everyone except 1 person had a 24 hour or 25 hour cycle.

Question 18

What conclusions can be drawn from Aschoff and Wever’s study? (1976)

Answer 18

Suggests that our cycle may be longer than 24 hours but this is entrained with exogenous zeitgeibers

Question 19

What evaluative points can be made about Aschoff and Wever’s study? (1976)

Answer 19

• Poor control
• They used artificial light which they assumed wouldn’t affect the results but studies have shown that it does and therefore acts as a confounding variable

Question 20

Outline Folkard et al’s study (1985)?

Answer 20

Had 12 people spend 3 weeks in a cave.
They all went to bed when it was 11pm and work at 7.45. Researchers gradually sped up the clock until it was just a 22 hour clock

Question 21

What were the results of Folkard et al’s study? (1985)

Answer 21

The participants were unable to adjust to the 22 hour clock

Question 22

What conclusions can be drawn from Folkard et al’s study? (1985)

Answer 22

We have strong circadian rhythms

Question 23

What is a practical application for research into circadian rhythms? (SW)

Answer 23

• Shift workers
• There is a reduced concentration a 6am
• known as a circadian trough
• Economical implications - worse work produced at 6am

Question 24

What did Boven (1996) find relating to shift work?

Answer 24

Found that 6am was the time that mistakes and accidents were more likely to occur

Question 25

What did Knutsson (2003) find?

Answer 25

People who work shifts are 3 times more likely to develop heart disease due to stress

Question 26

What do findings about shift work suggest should be changed?

Answer 26

The timing of shifts to maximise the efficiency of the individuals and reduce accidents

Question 27

What is a practical application for research into circadian rhythms? (DT)

Answer 27

• Drug treatments
• Rhythms affected by heart rate, digestion and hormone levels
• Has an effect on pharmokinetics which is the action of drugs on the body and how well they are absorbed and disturb distributed throughout the day
• Certain peak times during the day or night when drugs are likely to be at their most effective - led to guidelines of timings of drugs

Question 28

What is the issue with the use of case studies and small samples for research into circadian rhythms.

Answer 28

it means it is harder to generalise the findings

Not representative of the whole population

Question 29

What is the issue with individual differences when looking at circadian rhythms?

Answer 29

Individual samples may vary from 30-65 hours.

Question 30

What did Duffy et al find?

Answer 30

That some people have a natural preference to go to bed early or go to bed late