Sleep and Waking Flashcards
What behaviours occur in response to internal biological clocks?
- Seasonal migration.
- Mating seasons.
- Human menstrual cycle.
What is circadian rhythm?
A natural 24-hour cycle.
What is a free running circadian rhythm?
A 22-25 hour circadian rhythm cycle in the absence of natural light.
This is seen in those who are blind, or those on submarines.
What is the location of the body’s internal ‘master’ clock?
The Suprachiasmatic nucleus, located in the hypothalamus.
Where is the suprachiasmatic nucleus located?
In the hypothalamus, located above the optic chiasm.
What evidence implicates the SCN as the master internal clock?
Radioactive 2-deoxyglucose (2-DG) has been used to identify SCN activity.
What are the two chemical messengers released by the retinohypothalamic tract onto neurons in the SCN?
- Glutamate.
- PACAP.
When is glutamate released?
Glutamate is released in response to light, signalling the SCN that daylight has begun.
What is the role of PACAP?
It is thought to modulate the action of glutamate on the SCN - allowing for the response of different levels of light.
What does the SCN regulate and respond to?
The SCN regulates and responds to the hormone melatonin, secreted by the pineal gland.
Where is melatonin produced?
In the retina.
What is shift maladaptive syndrome?
40-80% of those working night shifts will experience disturbed sleep.
What is jet lag?
The interaction of internal and external clocks.
How many hours of sleep do 65+ year olds need?
7-8 hours.
How many hours of sleep do 26-64 year olds need?
7-9 hours
How many hours of sleep do 18-25 year olds need?
7-9 hours
How many hours of sleep do 14-17 year olds need?
8-10 hours
How many hours of sleep do 6-13 year olds need?
9-11 hours
How many hours of sleep do 3-5 year olds need?
10-13 hours
How many hours of sleep do 1-2 year olds need?
11-14 hours
How many hours of sleep do 4-11 month olds need?
12-15 hours
How many hours of sleep do 0-3 month olds need?
14-17 hours
Describe stage 1 of sleep.
- Light sleep.
- Muscle activity slows down.
- Occasional muscle twitching.
Describe stage 2 of sleep.
- Breathing pattern slows.
- Heart rate slows.
- Slight decrease in body temperature.
Describe stage 3 of sleep.
- Deep sleep begins.
- Brain begins to generate slow delta waves.
Describe stage 4 of sleep.
- Very deep sleep.
- Rhythmic breathing.
- Limited muscle activity.
- Brain produces delta waves.
Describe stage 5 of sleep.
- Rapid eye movement (REM sleep).
- Brainwaves speed up.
- Dreaming occurs.
- Muscles relax.
- Heart rate increases.
- Breathing is rapid and shallow.
What is used to measure brain activity during sleep?
Electroencephalogram (EEG)
What occurs during REM sleep?
- Increase in heart rate.
- Increase in blood pressure.
- Breathing becomes rapid and irregular.
- Increased blood flow to genital organs.
- Other major muscle groups are effectively paralysed.
- The sleeper may jerk or twitch.
When does dreaming occur?
During REM sleep and SWS.
Describe REM dreams.
REM dreams are lengthy, complicated, vivid and story like.
Describe SWS dreams.
SWS dreams are short episodes characterised by logical single images and a relative lack of emotion.
What do dreams of being unable to move in a dangerous situation mirror?
They mirror the muscle paralysis presented during the REM state.
What are lucid dreams?
Where the dreamer becomes aware of the fact they are dreaming, and are able to direct the dreams content.
What brain region is responsible for slow wave sleep (SWS)?
The forebrain.
What brain area appears to encourage sleep by inhibiting the arousal normally produced by the reticular formation?
The raphe nuclei (located in the brainstem).
What is the activity of the reticular formation associated with?
Wakefulness.
What is the Ascending Reticular Activating System (ARAS)?
A network of neural fibres fundamental to the regulation of arousal.
What role does acetylcholine play in sleep?
- Increases arousal.
- Increases REM sleep.
What role does noradrenalin play in sleep?
Increases arousal.
What role does serotonin play in sleep?
- Increases sleep time.
- Decreases REM.
What are two types of sleep disorders?
- Dyssomnias.
- Parasomnias.
What does dyssomnia involve?
Difficulties in the initiation, maintenance, timing and quality of sleep.
When does parasomnia occur?
When unusual behaviours disturb ongoing sleep.
What are some sleep disorders?
- Idiopathic Hypersomnia.
- Narcolepsy.
- Sleep Apnea.
- Sleep state misperception.
- Fatal familial insomnia.
What is Narcolepsy?
A chronic neurological disorder caused by autoimmune destruction of hypocretin-producing neurons.
What is Sleep Apnea?
Characterised by pauses in breathing or instances of shallow or infrequent breathing during sleep.
What is SIDS?
When a healthy baby, usually between the ages of 2-4 months dies while asleep.
