Biopsychology - 8) Biological Rhythms: Circadian Rhythms, Endogenous Pacemakers and Exogenous Zeitgebers

Question 1

Biological rhythm

Answer 1

A change in the body processes or behaviour in response to cyclical changes (regularly occurring changes) with the environment

Question 2

What are all biological rhythms regulated by?

Answer 2

Endogenous pacemakers
Exogenous zeitgebers

Question 3

Endogenous pacemakers

Answer 3

Internal body clocks that regulate biological rhythms (E.g. CNS in stimulation of pineal gland to release melatonin)

Question 4

Exogenous zeitgebers

Answer 4

External factors in the environment which reset our biological rhythms (E.g. light)

Question 5

What may influence/entrain biological rhythms?

Answer 5

Cues (E.g. meal times)

Question 6

What is a circadian rhythm?

Answer 6

A biological rhythm that occurs approximately once every 24 hours (E.g. the sleep/wake cycle)

Question 7

Sleep/wake cycle

Answer 7

1. Sunlight (exogenous) hits your eyes in the morning when you are asleep
2. Optic nerve carried a signal to the SCN (endogenous)
3. Sends a signal to your pineal gland to tell it that there’s incoming light
4. Pineal gland stops releasing melatonin (sleep hormone)
5. You wake up

Question 8

What will by the result of a messed up sleep/wake cycle?

Answer 8

Inadequate cognitive and bodily functioning

Question 9

How did Aschoff and Wever find that our sleep/wake cycle can become free running without inclusion of exogenous zeitgebers?

Answer 9

Placed participants in WW2 bunker in absence of environmental and social cues (exogenous zeitgebers)
Most participants displayed circadian rhythms between 24 and 25 hours
Rhythm retained without external cues

Question 10

Who study did Siffre conduct into circadian rhythms?

Answer 10

The Cave Study

Question 11

Process of Siffre’s original cave study

Answer 11

Spent 61 days and nights underground in a cave to test his internal body clock
No exogenous zeitgebers
Only influence was endogenous pacemakers

Question 12

When did Siffre emerge from the cave and what did he think the date was?

Answer 12

Emerged on 17th September and thought it was the 20th August

Question 13

Circadian rhythm of Siffre during the cave study

Answer 13

It exceeded 24 hours

Question 14

Conclusion of Siffre’s cave study

Answer 14

Supports role of exogenous zeitgebers
Shows that endogenous pacemakers have an influence on circadian rhythms
Shows strength of circadian rhythm as a free-running cycle

Question 15

Negative evaluation of Siffre’s cave study

Answer 15

Some have criticised research since it’s artificial, in particular the use of artificial light - it may artificially reset his body clock
Issue of validity as it’s a case study that only focuses on one individual
Living in a cave may have particular effects on the body (E.g. the cold climate)
He wasn’t isolated from all exogenous zeitgebers (E.g. contact with outside world), making it lack internal validity

Question 16

Real life application of research into circadian rhythms

Answer 16

Gap between someone doing a night and day shift now had to be 48 hours so people have time to readjust to alternative times of sleeping
Research has had impact on when medication should be taken (pharmaceuticals)