Sleep

Question 1

Explain the energy conservation hypothesis of sleep?

Answer 1

Warm blooded animals need to spend lots of time asleep to maintain a constant temperature. Small animals such as mice have a high metabolism. They therefore need more energy. They therefore use sleep as a period of inactivity to se less energy. Webb described this as the hibernation hypothesis.

Question 2

Which study supports the energy conservation hypothesis and why?

Answer 2

Zepelin and Retchshaffen 1974. They found that smaller animals with higher metabolic rates, sleep more than larger animals. This supports the view that those with high metabolisms use more energy.

Question 3

What is an exception to Zepelin and Rechtschaffen 1974?

Answer 3

Sloths, which are very large yet spend 20 hours a day sleeping.

Question 4

Explain predator avoidance and how it explains sleep?

Answer 4

Sleep is constrained by predator risk. Predators can sleep longer as there is little risk for them. However, prey has to sleep less as they are more vulnerable so they have to be vigilant. They only sleep when it is vital.

Question 5

How does Cappellini et al 2008 go against the energy conservation hypothesis?

Answer 5

They found a negative correlation between metabolic rate and sleep- smaller animals have higher metabolic rates and sleep less.

Question 6

which study supports they predator avoidance theory, and why?

Answer 6

Allison and Cicchetti 1976. They found that species who have a higher risk of predation sleep less.

Question 7

What is an acceptation to Allison and Cicchetti 1976?

Answer 7

Rabbits, they sleep the same amount as moles, and yet have a higher danger risk.

Question 8

How does unilateral sleep support the evolutionary approach?

Answer 8

This is where one hemisphere of the brain is awake while the other is asleep. Dolphins use this as they have to swim to the surface to take a breath. A dolphin that fell into a deep sleep would drown. Mukhometou 1987 showed that they must swap which hemisphere is asleep every two hours. Migrating birds also do this. This suggests that it has evolved in two separate groups of animals- and they actually sleep- suggesting tat sleep is very important from an evolutionary point of view.

Question 9

How is the evolutionary approach reductionist?

Answer 9

It oversimplifies sleep form the complex process it actually is.

Question 10

What advantages does the restoration theory have over the evolutionary?

Answer 10

The evolutionary appaoch fails to explain why we have a strong drive for sleep when sleep deprived, which is explained via the restoration theory, and why there are different stages and cycles of sleep.

Question 11

Why is a combined approach a better explanation of sleep?

Answer 11

Sleep cannot be explained by sleep alone. Horne 1988 suggestion of a distinguishing between core and optional sleep supports this.

Question 12

How is NREM and REM sleep’s evolution explained?

Answer 12

Animals that are more primitive, e.g. reptiles, only have NREM sleep. REM sleep appears to have evolved in birds and animals around 50 million years ago in birds and mammals. might be that NREM sleep developed for energy consumption and REM developed later to maintain brain function. This is supported by the gretare need for REM in infants whose brains are developing.

Question 13

Describe the sleep wake cycle?

Answer 13

The sleep wake cycle in humans follows a basic 24 hours cycle. However, within this, there is a another rhythm which consists if several repetitive cycles lasting around 90 minutes. This is a ultradian rhythm.

Question 14

What happens in the first stage of sleep?

Answer 14

Relaxed state, easily woken. Alpha waves and heart rate slow and temperature drops. This is light sleep.

Question 15

What happens in the second stage of sleep?

Answer 15

Relaxed state, easily woken. Theta waves and the heart rate slows and temperature drops. It is accompanied by burst of energy of an increased frequency- sleep spindles- and uncreased amplitude- k complexes. This is light sleep.

Question 16

What happens in the 3rd and 4th stage of sleep?

Answer 16

Delta waves, metabolic rate is the slowest, growth hormone is produced and it it hard to wake. This is deep sleep- SWS.

Question 17

Why is REM sleep called paradoxical sleep?

Answer 17

Brin and eyes are active by the body is paralysed.

Question 18

How many sleep cycles do people have a night and how long does each last?

Answer 18

5 and they last 90 minutes

Question 19

How does sleep cycles vary as the night goes on?

Answer 19

SWS only occurs in the first stage of sleep and REM occurs in all stages, increasing in length as the night goes on.

Question 20

How does Immune system explain narcolepsy?

Answer 20

In the 80’s, research suggested that it was linked to to a mutation of the immune system. Honda et al 1983 found an increased frequency of one type of human leukocyte- HLA- in patient, with more than 90% of narcoleptics showing this. HLA molecules coordinate the immune response and found of white blood cells. However, it is unclear how this would leaf to narcolepsy.

Question 21

How does the biochemical hypocretin explain narcolepsy?

Answer 21

In the 90’s, research has shown a link between low levels of hypocretin- a neurotransmitter- and the disorder. Hypocretin regulate sleep and wakefulness through interactions with the system that regulates emotion in the hypothalamus. Lin et al 1999 found that narcoleptic dogs had a mutation in a gene on chromosome 12 which disrupted the way that hypocretin was produced, which could explain the mechanism by which this occurs.

Question 22

Why is low levels of hypocretin the most promising explanation of narcolepsy?

Answer 22

Findings in dogs have been replicated in humans suggesting that they are accurate. For example, Nishino et al 2000 found that humans had low levels of hypocretin in the CSF.

Question 23

What research suggests that isn’t genetic, like other psychopathologies?

Answer 23

Minot 1998 found that there was no significant risk of one twin developing narcolepsy if the other twin had it.

Question 24

WHat are possible explanations for hypocretin abnormalities?

Answer 24

Brain damage, infection, stress, diet or an auto-immune attack. The auto immune aspect would link HLA abnormalities found by Honda et al. 1983.

Question 25

Which approach does most explanations for narcolepsy stem from, and how does that influence the treatment of the disorder?

Answer 25

Biological.
They would advocate the use of biological methods such as drug therapy to try and combat the onset in the day and to combat insomnia at night.

Question 26

How does the psychoanalytic approach explain narcolepsy?

Answer 26

It suggests that the sudden onset of sleep are ways of disguising sexual fantasies and arousal, and ways of coping and reducing the anxiety they may cause as suggested by Lehrman and Weiss 1943.

Question 27

Why isn’t the psychoanalytic approach widely accepted?

Answer 27

The disorder clearly has physiological elements, so an inclusive explanation of the disorder would need to refer to biological factors. If it was due to traumatic experiences, there could be studies into a relationship between the two, and if it was due to sexual fantasies, it may be more common.

Question 28

Why are explanations involving HLA and hypocretin seen as reductionist as an explanation of narcolepsy?

Answer 28

They attempt to reduce a complex multi-system disorder to malfunctions of specific biological disorders and ignore the other biological variable as well as those of environmental ones. Whilst physiological reductionism is necessary for research purposes, when it occurs at a theoretical level, it oversimplifies the disorders in an artifical way.

Question 29

How can explanations of narcolepsy been seen as deterministic?

Answer 29

It suggests that of the individual has the observed abnormality, they cannot bring the condition under their voluntary control. This may or may not be true for different individuals. There are certain behaviours that have helped control sleeping periods.

Question 30

What are problems with using animals in narcolepsy research?

Answer 30

Much of the research has been done on dogs. Whilst such research may be able to suggest which factors may be involved in animals, such findings cannot be generalised to humans. This is because the anatomy of humans and animals are different, and sleep patterns may be different.

Question 31

What is the nutshell definition for the evolutionary approach?

Answer 31

The evolutionary theory suggests that all behaviours animals perform serve some benefit to the individual and therefore ultimately the species. Behaviours that enable an animal to survive and reproduce in their environment are passed on via natural selection whereas those that aren’t are stamped out and so are not passed on. Because all animals that are possible to sleep do, it suggest that sleep aids survival.