Sleep Flashcards by Miranda Mcfall

Biological Explanation of Insomnia

Due to the malfunctioning of certain brain chemistry
Developed due to the prevalence of insomnia in populations who take drugs, are stressed or have existing conditions
As all of these can be damaging to body cells

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Gregory et al

Increased levels of anxiety can lead to increased levels of insomnia
- EV’s controlled for

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Narcolepsy 3 Explanations

1) Malfunction in systems which maintain REM
2) Increase frequency of HLA antigen in the immune system
3) Low levels of hypocretin neurotransmitter

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Narcolepsy- REM explanation

1960’s
Malfunction in the systems which maintain REM
Vogel- REM occurred at onset of sleep in narcoleptics, and they have abnormal REM at night
Explains some of the symptoms of the disorder which are also found in REM, eg. loss of muscle tone, hallucinations

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Narcolepsy- IMMUNE SYSTEM explanation

1980’s
Mutation of the immune system
Honda et al - increased frequency of human leukocyte antigen (HLA) - more than 90% of narcoleptics showed this
HLA coordinates the immune response

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Narcolepsy- HYPOCRETIN explanation

1990’s
Hypocretin is a neurotransmitter which regulates sleep and wakefulness
Link between LOW levels of hypocretin and the disorder
Lin et al- narcoleptic dogs had mutation in a gene on chromosome 12 which disrupted the way hypocretin was processed

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Narcolepsy- Mignot

There was no significant increased risk of one twin developing narcolepsy if the other twin had it
- So what causes the mutation on chromosome 12?

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Narcolepsy- What may cause the mutation on chromosome 12 if it is not genetics?

Brain injury
Infection
Diet
Stress
Auto-immune attack

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Sleepwalking- Incomplete Arousal

Recordings of brain activity show a mix of delta waves (SWS) and higher frequency beta waves (awake state)

A sleepwalker is in deep sleep (SWS) but is awaken, however the arousal is incomplete

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Sleepwalking Risk Factors

Sleep deprivation
Alcohol
Having a fever
Stress
Psychiatric Condition
Hormonal changes in puberty

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Two explanations for why sleep walking occurs more in children

1) Children have more SWS than adults
2) Oliviero- the system that normally inhibits motoractivity in SWS is not sufficiently developed in sleepwalkers. - more likely to be underdeveloped in children.

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Sleepwalking- Broughton’s study

The prevalence of sleepwalking in first degree relatives of a sleepwalker is 10 times greater than that for people in the general public

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Sleepwalking- Zadra et al

Studied 40 sleepwalkers in a sleep lab and prevented them for sleeping
1st night- 50% sleepwalked
2nd night- 90% (due to more stress from sleep deprivation)

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Infancy- Amount of sleep and percentage of REM

16 hours a day
50% REM
80-90% REM if premature

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Infancy- Features of sleep

Uncontinuous- shorter sleep cycles.

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Childhood - Amount of sleep and percentage of REM

12 hours a day

30% REM

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Childhood- Features of sleep

Experience parasomnias e.g. sleep walking and night terrors

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Adolescence - Amount of sleep and percentage of REM

9-10 hours a day

25% REM

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Adolescence - Features of sleep

Circadian rhythms shift into a PHASE DELAY where they delay sleeping and waking.

Adulthood- Amount of sleep and percentage of REM

8 hours a day

25% REM

Adulthood- Features of sleep

Increasing frequency of other sleep disorders e.g. insomnia

Old Age- Amount of sleep and percentage of REM and SWS

8 hours a day
20% REM
5% SWS
Mostly light sleep

Old Age- Features of sleep

Wake up frequently

Experience a phase advance of circadian rhythms - feel sleepier earlier and wake up earlier

Restoration Theory- Growth Hormones

Secreted during SWS

- Important for cell growth and restoration of body tissue

Restoration Theory- Immune System

- Consists of protein molecules and antibodies | - Regenerated during SWS

Evolutionary Theory- Zepelin and Rechtshaffen

Smaller animals sleep more than larger animals - however sloth exception (sleep for 20 hours)

Evolutionary Theory - Allison and Cicchetti (energy conservation)

Larger animals had less NREM than smaller animals. NREM conserves energy, but they have less of a need for this.

Evolutionary Theory- Allison and Cicchetti (predator avoidance)

Species with a high risk of predation did sleep less...however rabbit exception. They have a higher danger rating but sleep more than moles

Evolutionary Theory- Horne

Core sleep- SWS, what the body requires for restorative purposes Optional - REM and NREM- occupies unproductive hours and, in small mammals, conserves energy

Circadian Rhythm

Once a day, e.g. sleep-wake cycle

Infradian Rhythm

Once a month or year e.g., menstrual cycle, SAD

Ultradian Rhythm

Happens a few times a day e.g. sleep cycles, eating cycles

SCN

A group of neurons in the hypothalamus that have their own regular rhythms of firing activity

Pineal Gland

Controlled by the SCN, secretes the hormone melatonin

Melatonin

Increases feelings of sleepiness. Levels fall in light and rise in darkness

Siffre

- 6 months in a cave - Circadian rhythms settled at 25 hours - Occasionally erratic, drastically changing to 48

Ashchoff and Wever

- World war two bunker - Most p's had circadian rhythms of about 24-25 hours - Some of the p's extended to 29 rhythms

Folkard et al

- 3 weeks in a cave - Sped clock up to a 22 hour day - They settled at a 24 hour rhythm despite this - One participant adapted to the 22 hour

Tilley and Wilkinson

Daytime sleep is often between 1-2 hours shorter than normal, with REM being particularly affected

Knutson et al

Those who worked shifts for more than 15 years were 3 times more likely to develop heart disease

Czeisler et al

Introduced a forward rotating shift to a Utah chemical plant workforce who were struggling with stress. After 9 months, health improved, productivity increased by 25% and there were less personnel problems

Boivin et al

Artificial lighting- Had different groups of p's experienced different intensities of light brightness. The group with the 'very bright light' advanced their cycle the most, by 5 hours.

Phase advance

Occurs when travelling from West to East, most severe because it shortens the day so you might have to sleep when your body arousal is high

Phase delay

Occurs when travelling from East to West, least severe because it only extends the day

Recht et al

Analysed baseball results over 3 years. Teams from the East travelling to the West (phase delay) won 44% of games. Teams travelling from the West to the East (phase advance) won 37% of games.