biological rhythms: circadian rhythms

Question 1

biological rhythm

Answer 1

exert an important influence on the way the body system behaves

Question 2

what are biological rhythms governed by

Answer 2

• endogenous pacemakers
• exogenous zeitgeber

Question 3

what governs the sleep/wake cycle

Answer 3

• daylight (an exogeonous zieberger) makes us feel alert during the day and lack of it makes us feel dorwnsy at night time
• the internal pacemaker called the SCN provides information from the eye about light
• light can reset the SCN

Question 4

when was siffre’s cave study

Answer 4

1962

Question 5

Siffre cave study (1962)

Answer 5

• spent time in caves to study his own biological rhythm
• deprived of natural light and sound
• spent 2 months underground and his biological rhythm settled on 25 hours which made him believe that he had only been underground for 1 month

Question 6

when was aschoff and wever study

Answer 6

1976

Question 7

aschoff and wever (1976)

Answer 7

• 26 participants spent 4 weeks in a ww2 banker and were deprived of natural light
• 1 participants sleep cycle extended to 29 hours
• the rest had a circadian rhythm between 24 and 25 hours

Question 8

what does Siffre and Aschoof & Wever studies show

Answer 8

• that the natural sleep wake cycle may be longer than 24 hours
• but is entrained by exogenous zeitgebers associated with our 24 hours day

Question 9

when was folkard et al study

Answer 9

1985

Question 10

folkard et al study(1985)

Answer 10

• shows that we should not overestimate the effect of exogenous zeitgebers on our internal biological clock
• 12 participants lived in a dark cave for 3 weeks
• slept form 11:45pm to 7:45am
• the clock was gradually sped up so that 24 hours became 22
• only 1 participant adjusted
• concluded the existence of a strong free running circadian rhythm cannot be easily overcome by external factors

Question 11

strengths of circadian rhythm

Answer 11

1. shift workers
   - make more mistakes at 6am as it is a period of reduced concentration - circadiun trough
   - 3 times more likely to get heart attacks
   - real world economic implications
2. medical treatment
   - circadian rhythms coordinate the body’s heart rate, digestion and hormone levels
   - contributed to the field of chronotherapeutics - how medical treatment can be adminstrated that corresponds to a persons biological rhythm
   - aspirin for heart attacks are most effective taken at night
   - increase the effectiviness of drug treatment

Question 12

limitations of circadian rhythm

Answer 12

1. individual differences
   - generalisations are difficult to make
   - studies have very small sample sizes
   - sleep wake cycles vary from 13 to 65 hours in a differnt study
   - some preople prefer going to sleep early and waking up early - larks vs owls
   - even shiffe obserbed that his sleep wake cycle had slowed down since he was a young man