Sleep Flashcards
How is sleep defined?
Sleep remains the only universal behaviour known to biology with no clear consensus regarding a fundamental underlying function.
What do the different volumes of sleep mean about the animal?
The safer the animal feels the more sleep they have. Vulnerable animals will sleep very little and be easily aroused.
How long will a dolphin or whale stay awake for after giving birth?
24 hours a day for the first couple of weeks while the baby is particularly vulnerable.
How long will male sandpipers stay awake during spring breeding season?
active up to 23hours a day for nearly 3 weeks.
What is the function of hibernation?
Conserving energy while food is scarce.
What physiological things happen to an animal during hibernation?
Heart rate decreases and dendrites lose almost a quarter of their branches.
What is unihemispheric sleep?
One hemisphere (and the opposite eye) sleeps while the other remains awake.
What animals does unihemispheric sleep occur?
Aquatic mammals e.g. dolphins and many birds, and some reptiles.
What sleep waves occur during unihemispheric sleep?
Only slow-wave sleep (not REM sleep) occurs.
What is the inactivity theory?
The adaptive or evolutionary theory. Suggests inactivity at night helped animals survive as they did not injure themselves in the dark and were not killed by predators. This was therefore a trait passed on through natural selection.
What is a limitation of the inactivity theory?
Its always safest to be conscious, even if lying still in the dark.
What is the energy conservation theory?
Food is not always easy to come by, so an animal must conserve its energy. This is especially important during the night when it may be harder to find food.
What support is there for the energy conservation theory?
Support: energy metabolism is reduced during sleep (10% in humans and more in other species).
What limitations are there for the energy conservation theory?
Animals engaging in unihemispheric sleep are still using up energy.
What is the Restorative Theories?
During sleep there is restoration of what has been lost from the body whilst awake (e.g., muscle mass, tissue cells).
What support is there for the restoration theory?
Many major restorative functions (e.g., muscle growth, tissue repair) occur mainly in sleep.
What is the brain plasticity theory?
Sleep is a time in which the brain develops and changes i.e. creating new neurone and pruning old connections.
What support is there for the brain plasticity theory?
Sleep appears to be crucial for initial brain development in infants. Extensive research to suggest improvement in cognitive function (especially memory) following sleep.
What is circadian rhythms?
The human biological clock - like that of most organisms - synchronises to the Earth’s 24 hour rotation using signals from the environment, known as zeitgebers (time-giver).
Light is the strongest zeitgeber, although social cues also have an influence e.g. getting used to waking up at certain times.
Circadian rhythms: What will happen to your body in the morning when not slept all night?
After an entire night without sleep you will still begin to feel more alert in the morning when it becomes light.
Circadian rhythms: When there is no reason to wake at a specific time, what happens to peoples waking times in e.g. Germany?
People on the eastern edge will wake 30 mins earlier than people on the western edge consistent with the 30 mins sun difference timing.
What are ‘morning larks’?
Morning people. Wake early, alert, and reach their peak of productivity early.
What are ‘night owls’?
Evening people, take longer to warm up, reach their productivity later.
What are the downfalls of being a night owl in a morning lark world?
Lower grades, increased alcohol use, less happy overall.
Mammalian cells contain “circadian clocks”, what are these?
Collections of genes which regulate the switching on of other genes critical for cell physiology and metabolism.
What does damage to the suprachiasmatic nuclei cause?
Causes the peripheral clocks to lose their rhythmicity.
What does the pineal gland secrete?
Melatonin, a hormone that increases sleepiness.
How does melatonin feed back to reset the biological clock?
Through its effects on the receptors in the suprachiasmatic nucleus.
What can melatonin taken in the afternoon do for sleep?
It can phase advance the internal clock being used as a sleep aid.
What is the brainstem responsible for?
Mediating levels of arousal - including the cycle of Non-REM and REM sleep.
What does stimulation of the pontomesencephalon do?
Wakes someone when they are sleeping to increases alertness in someone who is already awake
How does a polysomnograph work?
It uses electrodes to record a combination of eye movement activity and EEG
What is stage 1 of sleep and what does the EEG show during it?
The transition period between sleeping and waking.
The EEG is dominated by irregular, jagged, low-amplitude waves of different frequencies.
What does stage 2 sleep show on an EEG?
Characterised by sleep spindles and K-complexes.
What physiological changes happen during stage 3 and 4 sleep?
Heart rate, breathing rate and brain activity decrease.
What does the EEG look like in stage 3 and 4 sleep?
Slow frequency (delta, 1-3hz), large amplitude waves become more common.
In stage 3 and 4 sleep, what happens to the neurons in the neocortical layers during slow wave sleep?
nearly all neurone in all neocortical layers are silent simultaneously.
What does the EEG show during stage 5 (REM) sleep and what does this indicate?
irregular, low amplitude, high frequency oscillations indicating increased neuronal activity which suggests lighter sleep.
What physical features happen during REM sleep?
Postural muscles in the body are more relaxed, higher variability of heart and breathing rate, erections/vaginal moistening and facial twitches.
What neuron is responsible for initiating REM and NREM sleep?
GABAergic neurone from the medulla
Name 3 sleep disorders
Narcolepsy, REM Behaviour disorder and sleep and violence.
What is narcolepsy?
A condition characterised by frequent periods of sleepiness during the day. it has a Clear genetic component.
What are the 4 main symptoms of narcolepsy?
Attacks of sleepiness during the day, occasional cataplexy, sleep paralysis and hypogogic hallucinations.
What cell do people with narcolepsy lack?
Hypothalamic cells that produce and release orexin - potentially due to an auto-immune condition.
Why cant orexin be administered to narcolepsy sufferers?
It cannot cross the blood-brain barrier.
How is narcolepsy mainly treated?
With stimulants e.g. Ritalin.
What is REM Behaviour Disorder (RBD)?
People with REM disorder move around vigorously during REM, often violently. They frequently injure themselves, others or damage property.
What disease is RBD strongly associated with ?
Parkinsons disease and also thought to be a very early pre-curser to the condition.
What is sleepwalking?
Complex movements carried out during sleep, sometimes dangerous. e.g., eating, rearranging furniture, driving cars, walking long distances
What stage(s) of sleep does sleep walking occur?
NREM sleep, could not occur during REM due to muscle atonia.
What are the risk factors of sleepwalking?
sleep deprivation, stress, alcohol
Who sleep walk?
Anyone can sleep walk but it runs in families and occurs mainly in children.
What is the approximate percentage of prevalence of sleep related violent behaviours?
2%
What is an inadvertent murder or suicide referred to rather than RBD?
NREM parasomnia
Violence during sleep: what are RBD episodes more likely to lead to?
Spousal injury during dreamed attack.
What physiological factors does sleep deprivation have a direct effect on?
Senses, thoughts, emotions and the brain.
What are the 4 different ways we can study sleep deprivation?
Experimentally depriving humans of sleep, experimentally depriving animals of sleep, examining case studies and examining sleep disorders e.g. insomnia.
What are the effects of sleep deprivation on the brain?
Reduced functional connectivity of the amygdala and executive control regions.
