4.1.2 - Sleep-Wake

Question 1

Circadian rhythm

Answer 1

biological and behavioral changes that occur as part of a cycle that lasts around 24 hours

Question 2

Ultradian rhythms

Answer 2

biological and behavioural changes that occur in a cycle that lasts less than 24 hours

Question 3

Melatonin

Answer 3

hormone released by the pineal gland typically at night-time to induce sleep as part of the sleep wake cycle

Question 4

Suprachiasmatic Nucleus (SCN)

Answer 4

an area of the hypothalamus that is responsible for regulating an individual’s sleep-wake cycle

Question 5

Pathway to the Release of Melatonin

Answer 5

1. Light sensitive neurons in the retinas of the eyes detect incoming light (from external environment)
2. Messages are sent to the brain (SCN) via the optic nerve (about light in external surroundings)
3. The SCN is our body’s internal body clock and regulates the circadian rhythm
4. At night when no light is detected the SCN sends a signal to the pineal gland to release melatonin (making us feel sleepy)
5. During the day when there is light, the SCN sends inhibitory messages to the pineal gland, meaning less melatonin is released (promoting wakefulness)