Cycles and Rhythms/ Jet Lag and Shift Work/ Theories of Sleep/ Life-Span Changes/Disorders of Sleep

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Biological Rhythms

Circadian- Have cycles that generally occur once every 24 hours. For example, we will usually go through the sleep-waking cycle once every day.

Infradian- Have cycles that occur less than once every day. For example, the menstrual cycle. Sabbagh and Barnard (1984) found that when women live together their cycles may synchronise. It isn't clear why, but it may be linked to pheromones (chemicals that can affect the behaviour or physiology of others).

Ultradian- Have cycles that occur more than once every 24 hours.

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Endogenous Pacemakers and Exogenous Zeitgebers

Endogenous Pacemakers

biological clocks

genetically determined

internal clock

scn-hypothalamus-pineal gland-melatonin production- less (increase)-more (decrease)

Exogenous Zeitgebers

external cues in the environment

light and clocks /social cues

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consequences of disrupting biological rhythms-Shif

Jet Lag- Phase Delay and Phase Advance. Jet lag is caused by the sudden creation of a large discrepamcy between the internal clock and the external world.

Schwartz et al (1995) found that baseball teams from the east coast of the USA got better results travelling to play in the west than teams based in the west did when travelling to play in the east.

Shift Work- Czeisler et al (1982) studied workers at a factory whose shift patterns appeared to cause sleep and health problems. The researchers recommended 21-day shifts (allowing more time for workers to adapt), and changing shifts forward in time (phase delay). After implementing the changes productivity and job satisfaction increased.

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Sleep States

Stage 1- is a bit like deep relaxation, with lowered heart rate, muscle tension and temperature. It's quite easy to wake people up.

Stage 2- has lower and larger EEG waves, with some quick bursts of high frequency waves called sleep spindles.

Stage 3- has even larger, slower waves.
Stage 4- has the largest, slowest waves of all, because it's the deepest stage of sleep. Metabolic activity is pretty low in general, and the sleeper is very hard to wake.
During the active stage, metabolic activity increases, and the body appears almost paralysed except for rapid eye movement (REM). The EEG pattern is almost like when you're awake. The cycle is repeated about five times during the night, but we only enter stages 3 and 4 in the first two. Periods of REM increase with ech cycle.

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Theories of the functions of sleep- Evolutionary t

Evolutionary theory relate to the environment, evolution and survival of the fittest.

Webb (1968) suggested that everyday sleep is similar to hibernation- sleep conserves energy at all times when it's harder to get resources (i.e. At night time). Using energy would ne ineffecient.
Meddis (1977) suggested that sleep helps animals safe. By being quiet and still, they are less likely to attract preditors (especially at night). However, sleep also makes animals vulnerable to preditors if discovered.
Restoration approaches suggest that sleepo restores the body's ability to function, after being busing during the day.

Evidence- Zepelin and Recltschaffen (1974) they found that animals that use more energy sleep for longer this supports the evolutionary theory that we sleep to gain and conserve energy.

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Theories of the functions of sleep- Restoration th

Restoration approaches suggest that sleep restores the body's ability to function, after being busing during the day.

Oswald (1980) suggested that SWS/non-REM sleep is for restoring bodily functions linked to physical activity and REM sleep is for restoring brain functions.
Horne (1988) distinguished betweened two types of sleep: core sleep, which is made up of stage 4 SWS (for body restoration) and REM sleep (for brain restoration), and optional sleep, which is made up of the other sleep stages. Although optional sleep is not necessary, having it can conserve energy.

Shapiro (1981) found that long- distance runners had more SWS after a race, implying that the exercise increased the need for bodily restoration.
Evidence- Jouvert (1967)- cats were placed on islands of flower pots floating in water. They could balance on the pot and enter stages 1-4 sleep, but in REM muscles would relax and the cats would fall into the water and wake up. REM sleep was deprived and following this experiment the cats died 35 days later. This supports the theory proving that we need REM sleep for brain restoration.

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Life span changes in sleep

The amount we sleep and our patterns of sleep change as we get older.

The older we get the less we tend to sleep-babies sleep up to 20hours a day, whilst most adults average 7-8 hours and people over 50 average only 6 hours.
Also, as we get older we tend to have less REM sleep- Kleitman (1963) found that newborn babies may spend 8-9 hours every day in REM sleep. Children have less REM sleep than infants, and adults have less than children.
Kales and Kales (1974) found that elderly people are more likely to wake up several times during their night's sleep than than younger people.
1)Most evidence for changes in sleep patterns comes from laboratory research using EEG recordings. These recordings are obtained by attaching electrodes to participants, which may disrupt their usual sleep patterns.
2)However, Empson (1989) suggests that after the first night participant adjust to the conditions and their sleep is representative of their usual patterns.

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sleep Disorders- Sleepwalking

Sleepwalking is a disorder associated with stage 3 and 4 sleep. It is recurring episodes of complex behavioural movements, each lasting from around 15 seconds to 30 minutes. The symptoms of sleep walking are sitting up, getting out of bed and moving around while in a state of sleep. Eyes are open but they are unfocused. This means they can’t find their way around or outside. They also have no recall of the event. Sleepwalking affects approximately 15% of children and 2% of adults. The causes are not fully known but it can be triggered by sleep deprivation, an irregular sleep schedule, stress or anxiety and also drugs e.g. antipsychotics or stimulants.

EEG monitoring confirms that sleep is maintained throughout sleepwalking, which occurs during slow wave sleep. This means that they are very unaware of their actions while they are sleeping. If the sufferer is unaware of their actions whilst sleepwalking, whether it being harmful and harmless they should take responsibility for it. However it is then up to the sufferer to seek help from a doctor or psychologist, in order for their sleep walking to decrease.

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sleep Disorders- Sleepwalking continued

Dauvilliers et al (2005) suggests their maybe a genetic component to sleep walking. He found that the concordance rate was higher in identical twins than non identical twins. This study suggests sleepwalking is biologically inherited. The study only looks at the biological approach. Sleepwalking could be related to the psychodynamic approach because sleep walking proceeds by night terrors. There could be a situation or issue bothering a person. It is then repressed into the unconscious leading to the person in their sleep unconsciously dealing with the situation by walking around (sleep walking). A way of dealing with this could be to transfer the problem from the unconscious to the consciousness of the persons mind through speaking about it (free association).

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sleep Disorders- Narcolepsy

Narcolepsy is a disorder causing sudden day time sleepiness leading to a person falling asleep for short periods of time (seconds or minutes). The symptoms of narcolepsy are weak muscles (cataplexy), dream like imagery (hypnagogic hallucinations) and muscle paralysis. Narcolepsy only affects 1 in 10,000 people and starts in adolescence and therefore it is a rare disorder. The symptoms can be dangerous and frightening for the sufferers (and other people), and may disrupt their personal and professional relationships.

The exact cause of the REM sleep advance is not yet known, although deficiencies in the brain proteins orexin and hypocretin (which plays a role in sleep patterns) and variations in chromosome 6 may be involved. This can be linked to the evolutionary theory that genetics could play a part in the cause of narcolepsy.

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sleep Disorders- Narcolepsy continued

Hypocretin is a chemical that’s involved in regulating arousal levels. It’s thought that narcolepsy may be caused by the body’s immune system attacking the cells that produce hypocretin reducing the body’s ability to regulate sleep. Therefore a person can’t help it if they have reduced levels of hypocretin. It’s biological, internal and that means something has gone wrong in the brain.

We know this because dogs with narcolepsy have been bred so that tests can be done to find out the causes of the disorder. The study tested dogs and although it might have given an insight about narcolepsy it cannot be generalised to humans. Another criticism of this study is that animals were used. It isn’t right for there to be more narcoleptic dogs suffering and therefore this is animal cruelty.

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