Biological Rhythms - Circadian Rhythms - Sleep/Wake Cycle

Question 1

Light deprivation studies aims

Answer 1

to assess the role of a persons internal biological clock (endogenous pacemakers)

asses whether the body clock can maintain its usual rhythms + cycles without external cues (exogenous zeitgebers)

Question 2

what happens when we remove natural light? (external cue)

Answer 2

biological clock is said to be ‘free running’

Question 3

name the 3 studies

Answer 3

• Siffre Cave studies
• Aschoff + Weaver Bunker study (1976)
• Folkard et al Cave study w/ speeded up clock (1985)

Question 4

outline siffra cave study

Answer 4

• no natural light / external sound

- spent 2-6 months underground

Question 5

Siffra cave study - findings

Answer 5

‘free running’ rhythm was a round 25hrs

still had a regular sleep/wake cycle

Question 6

outline Aschoff & Weaver’s Bunker Study (1976)

Answer 6

groups of ppts spent 4 weeks in a bunker

no natural light

Question 7

Aschoff & Weaver’s - findings 1

Answer 7

most ppts rhythms between 24-25hrs

1 ppts cycle extended to 29hrs

Question 8

what does both Siffra and Aschoff & Weaver’s study suggest?

Answer 8

internal clocks + external zeitgebers work together to ‘entrain’ sleep/wake cycle to 24hrs

Question 9

outline Folkard et al’s cave study (1985)

Answer 9

12 people in cave
12 weeks

sleep at 11:45pm - wake at 7:45am

Question 10

what did Folkard et al do to the clock in the study?

Answer 10

gradually sped up the clock

end of day = 22hrs

Question 11

Folkard et al - findings

Answer 11

only 1 person comfortably adjusted to new timings

Question 12

what does Folkard et al’s findings suggest?

Answer 12

strong circadian rhythm governed by internal biological aspects cannot be changed by zeitgebers

e.g. clocks