Stages Of Sleep

Question 1

What is an ultradian rhythm?

Answer 1

A biological process that repeats more frequently than once every 24 hours

Question 2

What kind of rhythm are the stages of sleep?

Answer 2

Ultradian rhythm

Question 3

What are the 2 features of electroencephalogram brainwaves?

Answer 3

• Frequency: How close the waves are to eachother (waves per second in Hz)

• Amplitude: The size of the brain wave (change in voltage)

Question 4

What are the 5 distinct patterns of brain wave?

Answer 4

Delta, Theta, Alpha, Beta, Gamma

Question 5

What 2 brain wave types distinguish sleep stages?

Answer 5

Theta and Delta

Question 6

How many sleep stages are there?

Answer 6

4

Question 7

What are stages 1-3?

Answer 7

NREM sleep

Termed N1, N2 and N3

Question 8

What is Stage 4?

Answer 8

REM sleep (Rapid eye movement)

Most dreams occur in REM sleep

Question 9

How long does one sleep cycle take?

Answer 9

Around 90 minutes

Question 10

How many times does the sleep cycle repeat over the course of a night’s sleep?

Answer 10

4-5 times on average

Question 11

What happens as the sleep cycle goes from N1 to N3?

Answer 11

Sleep becomes deeper

Less easily woken

Bain wave frequency slows but increased amplitude

Question 12

What does one sleep cycle look like?

Answer 12

REM -> N1 -> N2 -> N3 -> N2 -> N1 -> REM

Then repeats in next cycle

Question 13

What kind of sleep is N1?

Answer 13

Light sleep

Question 14

What happens in N1?

Answer 14

• Easy to wake and body may move suddenly (hypnic jerks)
• May be a sensation of falling, mild auditory or visual hallucination (hypnagogic hallucinations)

Question 15

What does EEG show in N1?

Answer 15

Theta waves

Slow frequency, high amplitude compared to awake

Question 16

What kind of sleep is N2?

Answer 16

Deeper sleep

Question 17

What happens in N2?

Answer 17

• Deeper than N1
• Harder to wake, the body is relaxed, heart rate and body temperature are lowered, the eyes are still

Question 18

What do EEG waves show in N2?

Answer 18

Sow theta

Occassional activity called sleep spindles (brief period of highly increased frequency) and K complexes (sudden dramatic high and low wave amplitudes)

Question 19

What kind of sleep is N3?

Answer 19

Deepest sleep

Question 20

What happens in N3?

Answer 20

• Very difficult to wake
• Body at its most relaxed with heart rate at its lowest

Question 21

What does the EEG show during N3?

Answer 21

Delta waves

Slow frequency, high amplitude

Slow wave sleep

Question 22

What happens during REM sleep?

Answer 22

Brain returns to active state passing back through N2 and N1

Similar to wakefulness, but body is paralysed

Question 23

How is REM characterised?

Answer 23

Rapid eye movement

Associated with dreaming, people report vivid dreams in this stage

Question 24

What study suggests REM is for mental recovery?

Answer 24

EEG of 10 patients recovering from drug overdose showed increased REM sleep

Question 25

What study suggests that N3 is for physical recovery of the body?

Answer 25

Ultramarathon runners showed longer sleep after intense physical activity with an increased proportion in slow wave sleep

Question 26

What study supports the idea that dreaming occurs most in the REM stage?

Answer 26

9 participants woken at different stages in their sleep cycle reported dreaming more frequently when woke in the REM stage

Question 27

How might the stages of sleep not be a simple process but adapt to the developmental needs of the individual?

Answer 27

Overall pattern of sleep stages if consistent, however there are some individual differences with newborn babies spending 80% of sleep in REM compared to 20-25% in adults

Question 28

How has the development of more sophisticated EEGs and other techniques helped improve our understanding of the sleep cycle?

Answer 28

In 2007, the thpught that there were 5 stages with N4 being another stage was scrapped and N3 and N4 were combined into just N3

Question 29

How has technology been developed due to understanding sleep stages?

Answer 29

Track sleep and help individuals improve sleep Avoiding waking in REM stops people feeling groggy and disorientated Leads to happier, healthier and more economically productive population

Question 30

What study shows that both the circadian and ultradian rhythms shouldn't be seen as seperate processes?

Answer 30

The longest period of REM sleep coincides with the lowest point in the circadian body temperature cycle Could mean that both processes could use the SCN