BIOPSYCH( Circadian rhythm)

Question 1

Define Circadian rhythm

Answer 1

A pattern or behaviour that occurs or reoccurs approximately every 24hours , which is set and reset by environmental light levels

Question 2

Why do we have a circadian rhythm?

Answer 2

To provide a distinct temporal niche for each necessary function of an organism. For rest and recovery

Question 3

How does the circadian rhythm operate

Answer 3

Cells exhibit daily rhythms and expression of clock genes and proteins thus they are able to keep time individually and in synchrony with each other SCN ( Suprachiasmatic nucleus) is synchronised to the physical , local environment by change in environment

Question 4

What processes does the Circadian rhythm regulate?

Answer 4

Sleep , Body temperature , Metabolism , Immune system , Reproductive system

Question 5

Explain sleep-wake cycle as a Circadian rhythm

Answer 5

Light detection wakes up up. When it’s light outside the brain detects this through the eyes . The SCN in the brain signals the body to stay awake. The hormone cortisol is released to keep us alert

When it gets dark , the SCN signals the body to release melatonin , a hormone that makes us feel sleepy. Body temperature drops , and the body prepares for sleep

During sleep the body rests and repairs itself. Different sleep cycles occur , including deep sleep and REM sleep.

In the morning as light increases , melatonin levels drop and the body wakes up

Question 6

Explain research supporting The importance of light

Answer 6

Hughes tested the circadian hormone release in 4 ppts stationed at the British Antartic Station

At the end of summer cortisol levels followed the familiar pattern , reaching the highest point as the ppts awoke , and their lowest as ppts went to bed

However after three months of darkness this pattern changed , with peak cortisol now in the afternoon rather than morning

This suggests extremes of daylight found in polar regions of the world may be responisble for variations in hormone release. However another researcher found no disruption of cortisol release

Question 7

What is the problem with research methodology supporting Circadian rhythms

Answer 7

In ,most studies ppts were isolated from variables that might affect their circadian rhythms like clocks, radios and daylight. However , they were not isolated from artifical light because it was believed that dim artifical light , in contrast to daylight , would not affect their circadian rhythms

Research suggests that this may not be true. CZEISLER altered ppts circadian rhythms down to 22hrs and up to 28 hrs by using dim artificial lighting alone, suggesting studies before may have been confounded by the presence of artifical light