Ultradian rhythms

Question 1

What is an ultradian rhythm?

Answer 1

A type of biological rhythm with a frequency of more than one cycle in 24 hours

Question 2

What are examples of ultradian rhythms?

Answer 2

Sleep cycle
Basic rest activity cycle

Question 3

How many stages of sleep are there and how long do these span?

Answer 3

5 stages, 90 minutes

Question 4

How can the sleep cycles be monitored?

Answer 4

EEGs

Question 5

Describe stages 1 and 2 of the sleep cycle

Answer 5

Light sleep - a person can be easily woken
At the beginning of this stage brainwave patterns become slower and more rhythmic (alpha waves), becoming even slower as sleep becomes deeper (theta waves)

Question 6

Describe stages 3 and 4 of the sleep cycle

Answer 6

Deep sleep - people are often difficult to wake at this stage
Involve delta waves which are slower still and have a greater amplitude than earlier wave patterns.

Question 7

Describe REM sleep

Answer 7

Rapid eye movement sleep - although the body is paralysed brain activity increases significantly, resembling that of an awake brain. It has been suggested that REM activity is highly correlated with dream content.

Question 8

Outline Dement and Kleitman (1957)

Answer 8

Monitored sleep patterns of nine adult participants in a sleep lab using EEGs. When the EEG suggested they were in REM sleep they would be awoken by a door bell and asked to write down the content of their dream. It was found that there is a significant correlation between eye movement and dream content. For example, one participant reported dreaming about climbing a ladder with his eye movements going up and down in this period.

Question 9

How is the BRAC a type of ultradian rhythm?

Answer 9

Because it takes place more than once in a 24 hour period