Sleep dreams and sleep disorders

Question 1

What are exogenous zeitgebers?

Answer 1

external cues from the environment that tell us it’s time to sleep such as sunlight, noise etc

Question 2

what are endogenous pacemakers

Answer 2

our internal bodily clocks that tell us it’s time to sleep

Question 3

What are Circadian rhythms?

Answer 3

They’re rhythms lasting about one day. The sleep wake cycle is the best example of one.

Question 4

What else, besides sleep, do circadian rhythms impact?

Answer 4

Body temperature, pain sensitivity, mental alertness, physical strength and the senses

Question 5

Explain how endogenous pacemakers actually work in keeping time.

Answer 5

a tiny cluster of around 20000 neurons in the hypothalamus control ur circadian rhythms. Known as the SCN this control centre is responsible for acting as your body’s internal pacemaker. The exact process is unclear but it’s known that environmental cues are important. For instance as sunlight decreases, the SCN receives signals to increase the production of melatonin (sleep hormone), making people more sleepy.

Question 6

What did Michel Siffre (1962) aim to discover

Answer 6

He wanted to find out what would happen to someone if they lived in a place without the exogenous zeitgeber of sunlight, i.e. a cave or mine.

Question 7

How long did Michel Siffre stay in a glacier for?

Answer 7

2 months

Question 8

What were the results of Michel Siffres experiment

Answer 8

He suffered below freezing temperatures and developed hypothermia. However he found that humans do have a 24-25 hour internal clock like plants. He only suffered from madness once and although his mind lost track of days, his body did not.

Question 9

Who found Michel Siffres experiment to be very useful?

Answer 9

Nasa

Question 10

Why do children need more sleep than adults?

Answer 10

To develop and function properly.

Question 11

How much sleep does a newborn need?

Answer 11

12-18 hours, meaning almost 9hrs is spent in REM sleep each day.

Question 12

How much sleep does a teenager need?

Answer 12

Between 8.5-9.25 hours and their body clocks are actually different from that of an adults.

Question 13

What is the Ultradian rhythm?

Answer 13

Just as the sleep-wake cycle functions according to a persons circadian rhythms, sleep itself has a cycle known as the ultradian rhythm.

Question 14

Describe the stages of non R.E.M. sleep

Answer 14

Stage 1 is a light stage of sleep. It’s the transition between wakefulness and sleep. The brain produces theta waves which are very slow. This lasts around 5-15 minutes. If you wake someone during this they are likely to think they weren’t sleeping.

Stage 2 lasts approx 29 mins. The brain begins to produce rapid rhythmic waves known as sleep spindles. Body temp decreases and HR slows.

Stage 3 is known as the delta stage as the brain begins to produce delta waves which are slow. It’s the transition between light sleep and deep sleep.

Stage 4 lasts approx 30 minutes and the brain continues to produce slow delta waves. Bed-wetting and sleep walking are most likely to occur near the end of this stage.

Question 15

Describe R.E.M. sleep

Answer 15

R.E.M. sleep is where dreaming occurs. During this stage, the eyes show rapid and random movement and their is an increase in respiration rates and increased brain activity. We have around 3-5 R.E.M. episodes a night. During this stage, although brain activity is high, muscles are actually very relaxed. Dreaming occurs due to this increase in brain activity and it takes up around 90-120 minutes of an adults night sleep.

Question 16

Give 3 examples of how we can study sleep

Answer 16

We can study sleep by using experiments such as Michel Siffre.
We can study sleep by using Polysomnographys (PSG).
We can study sleep by using observations and questionnaires

Question 17

Explain how a Polysomnography works.

Answer 17

It’s a test used to diagnose sleep disorders. Its a recording of the biophysical changes that occur during sleep. It’s usually performed at night. It monitors body functions including the brain.
It typically records a minimum of 12 channels requiring a minimum of 22 wire attachments to the patient. A minimum of 3 of these channels are used for the EEG (eye movement) and others are used to measure things like air flow, leg movement, heartbeat etc.

Question 18

What approach does Adam and Oswalds restoration theory (1983) come from?

Answer 18

The biological approach

Question 19

what does the restoration theory believe?

Answer 19

That sleep allows us to recharge our bodies and recover from fatigue. SWS enables bodily repairs whilst R.E.M. sleep is responsible for brain recovery.

Question 20

What experiments support the restoration theories belief that SWS enables bodily repairs

Answer 20

Sassin et al (1969) found that SWS resulted in an increase in GH which is responsible for the repair of the body.

Kreuger et al (1985) demonstrates that a lack of SWS is associated with reduced functioning of the immune system.

Question 21

What experiments support the restoration theories belief that R.E.M. sleep is responsible for brain repair?

Answer 21

Siegel (2003) strongly supports this as he discovered that there’s a strong link between the amount of R.E.M. Sleep and the maturity of offspring in other species. For instance, Platipus offspring are immature and require a lot more R.E.M. sleep to develop whilst dolphin offspring tend to be more mature and require less R.E.M. sleep as they don’t need to develop as much.

Question 22

What are criticisms of the restoration theory

Answer 22

If sleep is essential for restoration then sleep deprivation should have obvious negative consequences yet case studies if Randy Gardner and Peter Tripp showed that there are no real long term negative consequences to sleep deprivation.

The study relies too heavily on animal experiments and it can’t be assumed that the results from these can be generalised to humans. For instance, Adam and Oswald used Rechtschaffen (1983) as evidence to support the need for sleep to restore but a similar later experiment, Rattenborg (2005), found that the results were different.

If sleep is needed for restoration then increased physical activity should lead to a need for increased sleep. However Horne and Minard (1985) found that participants do get to sleep faster after a lot of exercise but they don’t sleep for longer.

Question 23

What did Rechtschaffen et al (1983) discover and how does this link to the restoration theory

Answer 23

They forced rats to stay awake by rotating a disc that they were standing on every time they started to fall asleep. After 33 days all the rats died and he concluded that this showed that sleep is essential for restoring life however many believe the rats may have died from stress. Adam and Oswald used Rechtschaffens experiment as evidence of the need for sleep but Rattenborg et al (2005) conducted the same experiment with pigeons and they experienced no ill consequences.