Circadian Rhythms

Question 1

circadian rhythm

Answer 1

• biological rhythm that operates on a 24hr cycle
• regulates bodily processes such as sleep/wake

Question 2

biological rhythms

Answer 2

• distinct patterns of changes in the body activity that conform to cyclical time periods
• can be influenced by internal body clocks or external changes to the environment

Question 3

what factors influence biological rhythms?

Answer 3

1. endogenous pacemakers
2. exogenous zeitgebers

Question 4

endogenous pacemakers

Answer 4

• internal body clocks
• main one: suprachiasmatic nucleus - bundles of nerves in hypothalamus that regulates sleep/wake cycle

Question 5

exogenous zeitgebers

Answer 5

• external factors that entrain our bio rhythms e.g. light
• works alongside EP to ensure we maintain 24 hrs

Question 6

examples of a circadian rhythm

Answer 6

sleep/wake cycle, core body temperature, hormone production

Question 7

process of the sleep/wake cycle

Answer 7

light- optic nerve - hypothalamus - suprachiasmatic nucleus- stimulates the release of melatonin from pineal gland - readies us for sleep

Question 8

research into circadian rhythms: case study

Answer 8

• siffre 1962
• spent 6 months in a cave without light
• sleep/wake cycle changed to 24.9 hrs
• shows existence of SCN and needing light to entrain it to stay in 24 hrs

Question 9

research into circadian rhythms: experiment

Answer 9

• folkard et al 1985
• studied 12 ppts in a dark cave who rose and set at the same time each day
• clock speed up so days became 22hrs
• only two able to adjust to the new routine showing dominance of EP to maintain 24hr clock

Question 10

strengths of circadian rhythms

Answer 10

PRACTICAL APPLICATIONS FOR SHIFT WORK
- more accidents around 6 am when concentration is shortest
- useful knowledge for employers to keep staff safe

APPLICATIONS IN DRUG TREATMENTS
- know what time best to administer to maximise effectiveness
- profes can treat illnesses more effectively and help those suffering

Question 11

limitations of circadian rhythms

Answer 11

USE OF CASE STUDIES
- siffre research only based on himself
- cannot generalise, changes may be due to something unique to siffre so lacks e.validity

POOR CONTROL
- siffre had a lamp, not total darkness
- czeisler adjusted ppts c.rhythms to 22-28 HR so siffre underestimates the influence of exogenous zeitgebers