Biopsychology: Lesson 10 - Circadian Rhythms

Question 1

What are biological rhythms and why did they evolve?

Answer 1

Biological rhythms - cyclical changes in physiological systems

They evolved because the environments in which organisms live have cyclical changes e.g. day/night, summer/winter etc.

Question 2

What are circadian rhythms?

Why are circadian rhythms important?

Answer 2

Any cycle that lasts 24 hours

They allow an organism to optimise their physiology and behaviour to best meet the varying demands of the day/night cycle

Question 3

What are circadian rhythms controlled by?

Answer 3

The suprachiasmatic nuclei (SCN), located in the hypothalamus

Question 4

What is the sleep-wake cycle?

Answer 4

The cycle of when we sleep and wake up which is determined by light and dark

Question 5

When are the strongest sleep drives in the sleep-wake cycle?

Answer 5

2: 00-4:00am
1: 00-300pm

Question 6

Which hormone induced sleep and how does it work?

Answer 6

Melatonin

It is released from the pineal gland during hours of darkness

Melatonin inhibits the neural mechanisms that promote wakefulness

Light suppressed the production of melatonin

Question 7

Why do people generally begin to feel tired towards the end of the day?

Answer 7

Sleep and wakefulness are also under homeostatic control

When we have been awake for a long time homeostasis tells us that need for sleep is increasing because of the amount of energy used during wakefulness

This homeostatic drive gradually increases throughout the day, reaching maximum in the late evening

Question 8

Evaluation of circadian rhythms

1. Chronotheraputics
2. Research may lack validity because it didn’t isolate people from artificial light
3. Individual differences
4. Temp vs light

Answer 8

1. Circadian rhythms are applied in chronotherapeutics. The time that the patients take medication is very important for treatment success. It essential that the right concentration of drug is released in the target area at the right time