6.4 Regulation of sleep–wake patterns by internal biological mechanisms

Question 1

Define Biological rhythm

Answer 1

A naturally occurring cycle of physiological, psychological or behavioural changes

Question 2

Define Biological clock

Answer 2

Innate timing that regulates one or more biological rhythms; see also suprachiasmatic nucleus

Question 3

Define Circadian Rhythm

Answer 3

A biological rhythm involving physiological, psychological or behavioural changes that occur as part of a cycle with a duration of about 24 hours

Question 4

Define Endogenous

Answer 4

originating within an organism

Question 5

Define Exogenous

Answer 5

originating outside an organism

Question 6

Define Ultradian rhtythm

Answer 6

A biological rhythm involving physiological, psychological or behavioural changes that occur as part of a cycle shorter than 24 hours

Question 7

Define the suprachiasmatic nucleus (SCN)

Answer 7

An area of the brain’s hypothalamus that regulates the timing and activity of the sleep–wake cycle (and other biological rhythms

Question 8

Define melatonin

Answer 8

A hormone secreted by the pineal gland in relation to the amount of light that is detected; influences alertness and drowsiness and timing of the sleep–wake cycle; a higher melatonin level is associated with greater drowsiness and vice versa

Question 9

What external factors trigger melatonin release.

Answer 9

Lack of sunlight.