BIOPSYCHOLOGY - circadian rhythms

Question 1

what are biological rhythms?

Answer 1

distinct patterns of changes in the body activity that conform to cyclical time periods.
Influenced by internal body clocks ( endogenous pacemakers) and external changes to the environment ( exogenous zeitgebers)

Question 2

what are circadian rhythms?

Answer 2

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

Question 3

what is an example of an exogenous zeitgebers?

Answer 3

light

Question 4

how can the sleep/wake cycle be governed by our body?

Answer 4

by internal body clocks known as endogenous pacemakers such as SCN.

SCN - suprachiasmatic nucleus

OR
by exogenous zeitgebers such as light = can reset SCN

Question 5

where is the SCN located?

Answer 5

lies above the optic chiasm which recieves information from the eye about light.

Question 6

outline Siffre’s cave study.

Answer 6

• spent extended periods underground to study his own biological rhythms
• deprived of exposure to light and sound
• had supply of food and drinks

Question 7

outline the findings of Siffre’s cave study.

Answer 7

• resurfaced mid September 1962 but believed it to be august
• spent two months
• 10 yrs later = re did this experiment but for 6 months in a texan cave

Question 8

conclusion of Siffre’s study?

Answer 8

his biological rhythm settled down to one that was 25 hours though he did fall and wake up on a regular schedule.

Question 9

Outline Aschoff and Wever (1976)

Answer 9

• Ps spent 4 weeks in a WW2 bunker = deprived of natural light
  FINDINGS = all Ps sleep/wake cycle extended to 29 hours
  one Ps sleep/ wake cycle displayed a circadian rhytm of 24 and 25 hours.

Question 10

Outline Folkard et al (1985).

Answer 10

• 12 ps lived in a dark cave for 3 weeks
• went to bed at 11:45 and awoke at 7:45
• researchers sped up the clock gradually (ps did not know this)
• 24 hour day eventually lasted 22 hours

FINDINGS: only one Ps was able to comfortably adjust to the new regime
= SUGGESTS EXISTENCE OF STRONG FREE-RUNNING CIRCADIAN RHYTHM THAT CANNOT BE EASILY OVERRIDDEN BY EXOGENOUS ZEITGEBERS.

Question 11

give strengths of research into circadian rhythms.

Answer 11

+ provides an understanding of desynchronisation
eg Boivin et al= night workers engaged in shift work = experience period of reduced concentration = mistakes and accidents more likely.
= research inro sleep/wake cycle may have real world economic implications in terms of how to best manage worker productivity.

+ improve medical treatments
circadian rhythms coordinate a number of the body’s basic processes such as heart rate and digestion. This has lead to field of chronotherapeutics = how medical treatment can be administered in a way that corresponds to a person’s biological rhythms.
eg aspirin
= circadian rhythms can help increases effectiveness of drug treatments

Question 12

give limitations of research into circadian rhythms.

Answer 12

• COUNTERPOINT = studies investigating the effects of shift work use correlational methods = difficult to establish whether desynchronisation of the sleep/wake cycle is actually a cause of negative effects, there may be other factors.
  eg Solomon (1993) = high divorce rates in shift workers may be due to other influences such as missing out on important family events = may not be biological factors that create adverse consequences
• generalisations are difficult to make
  studies such as Aschoff, Wever, Siffre based on very small samples = unrepresentative as sleep cycles can very widely from person to person. Even siffre found that in a later study his own sleep cycle slowed down. = therefore difficult to use research data to discuss anything more than averages.