Biopsychology: Circadian rhythms

Question 1

What is meant by biological rhythms?

Answer 1

cyclical patterns within biological systems that have evolved in response to environmental influences

Question 2

What 2 things are biological rhythms governed by?

Answer 2

1. The body’s internal biological ‘clocks’ (endogenous pacemakers)
2. External changes in the environment (exogenous zeitgebers)

Question 3

What cycle does the circadian rhythm operate on?

Answer 3

24 hour cycle

Question 4

What can reset the body clock?

Answer 4

Environmental events (exogenous zeitgebers)

Question 5

What’s an example of a exogenous zeitgeber?

Answer 5

Light levels

Question 6

Give two examples of the circadian rhythm?

Answer 6

• sleep/wake cycle
• core body temperature

Question 7

What does the sleep/wake cycle explain?

Answer 7

It explains why we are drowsy at night-time and alert during the day

Question 8

What is the sleep/wake cycle also governed by? and what is it called?

Answer 8

An internal (endogenous) pacemaker - a biological clock called the suprachiasmatic nucleus (SCN)

Question 9

Where does the SCN lie and do? and what can reset it?

Answer 9

• Lies in the hypothalamus
• Provides information from the eye about light
• Exogenous zeitgebers (light) can reset the SCN

Question 10

What are researchers interested in studying?

Answer 10

Seeing what would happen if our biological ‘clock’ ran by itself without the influence of external stimuli (e.g. light)

Question 11

Who conducted a study in a cave? and what was the study called?

Answer 11

• Siffre
• Siffre’s cave study

Question 12

What was the AIM, METHOD and RESULTS of Siffre’s cave study?

Answer 12

AIM: To study the effects of his own biological rhythms

METHOD:
- Deprived of exposure to natural light & sound
- But with access to adequate food and drink

RESULTS:
- His ‘free running’ biological rhythms settled down to one that was just beyond the usual 24hrs (around 25hrs)
- though he did continue to fall asleep and wake up on a regular schedule

Question 13

When did Siffre resurface and what did he think?

Answer 13

Mid-september 1962 after two months in the caves believing it was mid-august

Question 14

Who else did research into circadian rhythms? and what was this study called?

Answer 14

Aschoff & Wever’s bunker study

Question 15

What did Aschoff & Wever’s bunker study do?

Answer 15

Convinced a group of participants to spend 4 weeks in a World War 2 bunker deprived of natural light

Question 16

What happened to the circadian rhythms of the participants in Aschoff & Wever’s bunker study?

Answer 16

All by 1 participant displayed a circadian rhythm between 24-25 hrs the rest extended to 29 hours

Question 17

What do both study’s suggest?

Answer 17

That the ‘natural’ sleep/wake cycle may be slightly longer than 24 hours

• but that is entrained by exogenous zeitgebers associated with our 24-hour day (such as the number of daylight hours, typical mealtimes, etc)

Question 18

One strength of the research into the circadian rhythm

Answer 18

POINT: Provides an understanding of the adverse (unfortunate) consequences that occur when the rhythms are disrupted.

EVIDENCE: Night shift workers will experience reduced concentration at around 6AM.

EXPLAIN: Shift workers are more likely to develop heart disease than people who work typical work patterns.

LINK: Research could have real-world economic applications in terms of how to manage productivity.

Question 19

CA for the strengths of shift work

Answer 19

• Tend to use correlational methods
• Hard to establish if the desynchronisation of the sleep-wake cycle was the cause
• May be due to high divorce rates or the strain of missing family events
• Therefore it may not be biological factors creating adverse consequences

Question 20

Another strength of the research into the circadian rhythms

Answer 20

POINT: Has been used to improve medical treatments

EVIDENCE: Aspirin (treatment for heart attacks) is most effective taken last thing at night

EXPLAIN:
- as it reduces blood platelet activity
- which can reduce the risk of heart attacks
- Heart attacks most likely to happen early morning= so timing of Aspirin is important

LINK: Shows how circadian rhythm can help increase effectiveness of drug treatments

Question 21

One limitation of the research into the circadian rhythms

Answer 21

POINT: Generalisations are difficult to make due

EVIDENCE:
- very small samples of participants (e.g. 1 in Siffre’s)
- Individual differences (sleep/wake cycle different for everyone, between 13-65 hrs)
- Some like going to bed early & rising early (‘larks’)

EXPLAIN: Difficult to use the research data to discuss anything more than averages

LINK: May be meaningless then