Chapter 4 Definitions

Question 1

Circadian rhythms

Answer 1

Biological rhythms with cycles that occur on a 24 hour cycle (Eg. Sleep/wake pattern, alertness, body temperature etc.).

Question 2

Ultradian rhythms

Answer 2

Biological rhythms with cycles shorter than 24 hours (Eg.REM/NREM cycles).

Question 3

Somnambulism

Answer 3

Sleepwalking.

Question 4

Night terrors

Answer 4

When a person wakes up (often screaming) in sheer terror but rapidly returns to sleep and has no recollection of the event the next morning.

STAGES 3&4 NREM - Common in young children (3-6 years old).

Question 5

Hypnogram

Answer 5

The graph which the REM/NREM cycle is plotted on.

Question 6

Hypnogogic state

Answer 6

The relaxed state that occurs during the transition from being awake to being asleep.

Question 7

Hypnic jerk

Answer 7

Involuntary muscle twitches that cause us to jolt.

Question 8

Muscle Atonia

Answer 8

The total relaxation of muscles to the point of paralysis when in REM sleep.

Question 9

Hypnopompic state

Answer 9

Period between being asleep and waking up, a time when the brainwaves are predominantly alpha waves.

• Hypnopompic (vivid) images are often seen during this phase.

Question 10

Explain the survival theory of sleep

Answer 10

Suggests that organisms undertake periods of inactivity, or sleep, in order to enhance their chances of survival. They do this by conserving energy and protecting themselves during periods of the day when they are most vulnerable.

Question 11

Explain the restorative theory of sleep

Answer 11

Suggests that sleep allows us to recharge our bodies, recover from the physical/physiological work during the day and allows our bodies’ growth processes to function.

Question 12

Infradian rhythms

Answer 12

Biological rhythms with cycles longer than 24 hours (Eg. Menstrual cycle).