Chapter 4 - Stages of Sleep

Question 1

Infradian rhythms

Answer 1

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

Question 2

Circadian rhythms

Answer 2

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

Question 3

Ultradian rhythms

Answer 3

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

Question 4

CHARACTERISTICS OF SLEEP AS AN ASC

Answer 4

.-.

Question 5

What % of sleep time is spent in NREM 1-4 and REM?

Answer 5

Stage 1 (NREM): 10%
Stage 2 (NREM): 50%
Stage 3 (NREM): 10%
Stage 4 (NREM): 10%
REM: 20%

Question 6

On average, how many REM/NREM cycles does an adult have each night?

Answer 6

Six.

Question 7

How long does each stage last?

Answer 7

1 NREM - About 5 minutes.
2 NREM - About 20 minutes.
3 NREM - Brief.
4 NREM - First is about 30 minutes, progressively gets shorter.
REM - First is about 10 minutes, progressively gets longer.

Question 8

When do sawtooth waves occur?

Answer 8

REM.

Question 9

When do hypnic jerks and the hypnogogic state occur?

Answer 9

Stage 1 NREM.

Question 10

When does no eye movement occur?

Answer 10

Stages 3 and 4 NREM (and a bit of stage 2 NREM).

Question 11

States the type of brainwaves in each stage of sleep.

Answer 11

1 NREM - Alpha being replaced by theta.
2 NREM - Theta.
3 NREM - Theta becoming delta.
4 NREM - Delta (slow-wave sleep).
REM - Beta-like (irregular).

Question 12

Heart and breathing rate in each stage of sleep?

Answer 12

1 NREM - Irregular.
2 NREM - Slower and more regular.
3 NREM - Slower and more regular.
4 NREM - Slow and regular (slowest and most regular of all stages).
REM - Increase and fluctuations (up and down); irregular.

Question 13

Body temperature in each stage of sleep?

Answer 13

1 NREM - Normal.
2 NREM - Lower.
3 NREM - Lower.
4 NREM - Lowest.
REM - Unregulated.

Question 14

When are night terrors, sleepwalking and bedwetting likely to occur?

Answer 14

Stages 3 and 4 NREM.

Question 15

When do nightmares occur?

Answer 15

REM.

Question 16

Somnambulism

Answer 16

Sleep walking.

Question 17

Night terrors

Answer 17

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.
- Is common in young children (3-6 years old).

Question 18

Hypnogram

Answer 18

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

Question 19

Hypnogogic state

Answer 19

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

Question 20

Hypnic jerk

Answer 20

Involuntary muscle twitches that cause us to jolt.

Question 21

Hypnopompic state

Answer 21

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 22

Explain the Survival Theory of Sleep.

Answer 22

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 23

Explain the Restorative Theory of Sleep.

Answer 23

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 24

Evidence that supports Survival Theory?

Answer 24

• Small, vulnerable animals sleep less than large, resilient animals because they are constantly at risk of death.
• Sleep conserves energy.
• Sleep is less necessary for animals that need more food (Eg. Cows).

Question 25

Evidence that supports the Restorative Theory?

Answer 25

• Growth hormone is released during sleep.
• Sleep increases immunity (Immune cells are released).
• Sleep consolidates memories.
• Prepares body for action the next day.

Question 26

Criticisms of Survival Theory?

Answer 26

• Assumption that sleep is useful, but not essential (does not explain why we MUST sleep).
• Assumption that sleep is a way to hide from predators (sleeping can be dangerous).

Question 27

Criticisms of Restorative Theory?

Answer 27

• Assumption that more sleep is needed when we are physically active (what about people in wheelchairs?)
• Assumption that body rests during sleep (During REM, energy is expended so protein synthesis is slowed).