Sleep, Dreams and Sleeping Disorders and Memory. - PowerPoint Presentation

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Sleep, Dreams and Sleeping Disorders and Memory.

You will need to know:

How 3 different approaches attempt to explain each topic.

At least 2 key studies for each topic.Slide3

We will look at:

Biological Approach

Cognitive Approach

Psychodynamic (psychoanalytic) approachSlide4

This approach believes that all behaviour is a result of systems within the body:

Genes (hereditary)

Biochemical Imbalance (

e.g hormones)Neuroanatomy Problems. Slide5
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Last approx. one day.

Sleep and wake cycle – body temp, urine production, etc. This is called homeostasis – the control of internal conditions.

Endogenous pacemakers – internal biological rhythms.

Exogenous zeitgebers – external factors which affect our biological rhythmsSlide7

Internal or External?

Siffre

, 1975 – When people deprived of zeitgebers they still maintain a cyclical rhythm but it extends to 25 hours. Internal and external factors work in unison.

Menaker et al, 1978 – cut the suprachiasmatic nucleus (SCN – the brain’s internal clock, a bundle of nerves situated in the hypothalamus) from a hamster’s brain and found a disruption to the hamster’s circadian rhythms Slide8

The SCN

The main Endogenous PacemakerNeurones project from the SCN to the pineal gland which releases melatonin to induce sleepiness.Slide9

Biorhythm that lasts less than 24 hours,

eg

brain activity during sleep.Electroencephelogram

(EEG) measures the varying brain activity during sleep and has found 5 stages.The first four and non REM (nREM) stages in sleep gets progressively deeper

The final stage is REM sleep – paralysis, eye movement, dreaming. EEG activity would suggest that person is actually awake.Slide10
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Light

Light can be detected through other areas of the body, not just the eyes, and can be a powerful

zeitgeber.

Campbell and Murphy, 1998- found that shining lights on the back of knees could alter circadian ryhthms.Slide13

Social Factors

Luce and

Segel, 1966. People who live in the Arctic Circle maintain a constant sleep pattern despite 6 months of constant darkness in the winter.

This suggests that social factors can override light as a powerful zeitgeber.Slide14

Stimulants and Depressants

Alcohol –

decreases time taken to fall asleep but lessens the amount of time spent asleep.

Caffeine - While a little caffeine increases wakefulness, too much can cause insomnia, jitters, headaches, irregular heartbeat, racing heart and anxiety. Avoid caffeine after 4pm!Nicotine

– The addictive affect of nicotine means that smokers tend to wake in the night craving cigarettes (30 mins-2 hrs after last cigarette.

Smokers are much more likely than non smokers to report trouble falling and staying asleep (Philips and Danner, 1995)Slide15

Problems can occur when disruption to rhythms happen quickly

eg

jet lag and shift work.

Problems include poor attention span, impaired reaction time and reasoning skills.

Going from East to West causes minimal issues – gain time. However, going from West to East means you lose time and that’s when problems occur.

In the East it is night time but you have just come from the West – your temp and metabolic rate is at it’s peak making it difficult to fall asleep.Slide16

Schwartz et al, 1995. Studied baseball teams from West and East coast of America. East coast teams who were playing on the West coast won significantly more games than West coast teams playing on the East coast.Slide17

Chemicals

– Melatonin supplements can help to reset the body clock. Used by American military pilots. However, these are not yet licensed in the UK.

Light

– The SCN is sensitive to light and this can contribute to jet lag. SIK1 is a protein that can counteract the affects of light. A 2013 study at Oxford Uni reduced the SIK1 in mice and then exposed them to artificial light to recreate the feeling of jet lag. The reduction in SIK1 meant that it took them just 6 hours to recover rather than the usual 6 days.

Food

– fasting can also alter biorhythms and therefore help to counteract jet lag.Slide18

More frequent shift changes result in more negative effects.

Eg

fatigue, sleep disturbance, memory loss, mood swings, reduced productivity and low staff morale. Major industrial disasters,

eg Chernobyl, tend to happen in the early hours as well as fatal car accidents.Slide19

Czeisler

, et al, 1990. Exposure to bright light and darkness to treat physiologic

maladaptation to night work.

Aim – to evaluate if exposure to bright light at night and darkness in day can treat maladaptation due to night work.PPT –

8 men – 22-29 years old.

Method

– 2 week study. Control condition and treatment conditionSlide20

1st week baseline study 2

nd

week night shift work.Results – Treatment study slept for 2 hours longer than control.

Sig. shift in body temp nadir between week 1 and 2 and between control and treatment condition.Behavioural changes –same behaviour shown but shown later in treatment condition.

Alertness – Treatment condition

sig

higher than control by end of week 2.Slide21

Conclusion

– Maladapatation

of the human circadian rhythm to night work, with its associated decline in alertness performance and quality of daytime sleep can be treated effectively with scheduled exposure to bright light at night and darkness during the day.

Evaluation?Slide22

Ecological Theory

We adapt and evolve to fit in with our environment.

Meddis, 1979 – Protection theory – length of sleep depends on whether the animal is predator or prey. Prey sleep less because they are vulnerable.

Webb, 1982 – hibernation theory – sleep to conserve energy when there is little food (winter). Sleep lowers metabolic rate.Slide23

Restoration Theory of Sleep. Oswald, 1966

Sleep restores depleted resources of energy, repairs cells and restores homeostasis.

During

nREM sleep body releases more growth hormone which could help to restore cells.Shapiro, 1981 – studied ultra marathon runners and found that for the next 2 nights they slept for approx

90mins longer than usual. Stage 4

nREM

sleep (when growth hormone is released) increased from 25% of sleep to 45%. REM sleep decreased.Slide24

Restoration theory contd.

Oswald and Hartman, 1984 extended this theory to look at REM sleep and how it helps to restore the brain.

Sterne and Morgan, 1974 – neurotransmitter levels restored during REM sleep.

Would explain why babies spend 9 hours of their day in REM sleep compared to adults 2 hours – their brains are still growing and developing.Slide25

Restoration theory – supporting evidence.

Disruption at stage 4 =

fibrositis

(lower back condition caused by muscle wasting)Following trauma to the brain people spend longer in REM sleep for next 6 weeks.Explains different sleep needs for different life stages.How does it explain the varying sleep patterns of different animals if sleep only serves this one purpose?

Eg

lions sleep lots, herbivores sleep little – lifestyle seems to explain this more than just endogenous factors.Slide26
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I have asked you to keep a diary of your dreams for the last week.

Think about the dreams you have had so far, can you make sense of them?

Are they organised or bizarre and random?

Can you make links between them and what has happened through the day?Does there seem to be any links between the content of dreams?What do you think has caused them? Slide28

Series of visual images, actions and emotions.

Not just images – blind people have been shown to have just as vivid dreams even though they don’t see anything.

Nightmares are much more likely if the person is anxious during waking hours and people who are feeling sad or depressed are more likely to have dreams about loss and failure (Oswald 1980)Slide29

Dement and

Kleitman

, 1957Aims – (1) to find a correlation between REM sleep and dreams, (2) the estimation of duration of dreams and length of eye movement and (3) association between the pattern of eye movement and context of dream.

See handoutSlide30

Hobson and

McCarley

, 1977Based on many years of electrophysiological research into the brain mechanisms.

Random bursts of neural activity are made sense of by the brain and expressed through dreams.Integrates sensory and motor information with memories and expectations.Slide31

Activation = entering into REM sleep triggers the mechanism based in the brain stem which arouses the sensory and motor information which forms the basis of our dreams.

Synthesis = how we make sense of this activation and how it is expressed in your dream.

Eg – if neurons are fired into the part of the brain that is responsible for balance we might dream that we are falling.Slide32

Gillin

et al, 1985 – injection of the neurotransmitter acetylcholine (responsible for initiating REM sleep) increased both the amount of REM sleep and dreams – supporting the idea that neurons are indeed responsible for our dreams.

However, dreams are sometimes influenced by real events. How can random firing explain this?Slide33

Crick and

Mitchison

, 1983

While we dream the brain sifts through the information and gathers inform and gets rid of any unwanted material – “We dream to forget”.

Information creates a physical connection in the brain which can overload our cortex and disrupt the efficiency and organisation of memory if not ‘cleared out’.

These networks are erased by impulses bombarding the cortex.

The content of dreams represents these parasitical thoughts and are wiped from the memory.Slide34

Crick and

Mitchison

believed that the fact that spiny anteaters and dolphins don’t dream supports their theory. Both of these animals have relatively large frontal

cortexes. Possibly to store all the information they can’t lose during sleep? However, not all dreams are random – some have a clear narrative to them. How can this theory explain these kind of dreams?

In 1986 they revised their theory to only include bizarre imagery dreams.