Sleep Flashcards
How many hours of sleep are needed for different stages in a human’s life?
16 hours for, 9 for teenagers, 7-8 for adults
Is there any adaptations for sleep deprivation?
No, when sleep is missed it is not made up
Describe stage 1, 2, 3, 4 and REM sleep
Stage 1 - intermediate stage between waking and sleeping, theta activity
Stage 2 - shows sleep spindle and K complexes
Stage 3 & 4 - Begin slow wave sleep with delta activity
REM sleep - most like waking with theta and beta activity
What are the differences between Slow Wave Sleep (SWS) and Rapid Eye Movement sleep (REM)?
REM - characterised by EEG desynchrony, lack of muscle tone (paralysis) and rapid eye movement
SWS - EEG synchrony, moderate muscle tone and absence of eye movement
What is insomnia and how is it treated?
Affects 25% of the population, reducing quality of sleep. People often report less sleep than they actually get.
Pharmacological treatments try to treat quality of sleep
What is sleep apnea?
Condition where breathing ceases during sleep
What is narcolepsy?
A sleep disorder whose primary symptom is a ‘sleep attack’, where patient suddenly falls asleep
What is cataplexy?
Where, in response to high excitement, sleep attack is provoked where eyes are open and consciousness is maintained but muscle tone is lost
What is sleep paralysis?
Condition where paralysis is present after waking with hypnagogic hallucinations, belived to be a result of REM dreaming and paralysis not being turned off
How is narcolepsy usually treated
With modafinil
What is REM sleep disorder and what is it believed to be caused by?
- Lack of REM paralysis causes people to act out their dreams
- Believed to be due to accumulation of alpha synuclein in neurons that can be treated with benzodiazepine
Name 3 slow wave sleeping disorders associated with childhood
Sleep walking, bed wetting and night terrors
What 3 types of neurone are active during waking and inactive during sleep?
- Noradrenaline
- Serotonin
- Orexinergic
What area was described by von Economo as producing encephalitis lethargia when damaged?
Preoptic area of the hypothalamus, with the key area being the ventrolateral preoptic area (vlPA)
- Damage to area produces insomnia in rats
- Stimulation induces sleep
What 3 systems are believed to interact to produce arousal and sleep?
- Mutual inhibition between sleep promoting areas on vlPA and Brain stem/forebrain arousal systems
- Orexinergic neurones in lateral hypothalamus activate brain stem/forebrain maintaining switch ‘on’
Name 2 things that affect orexinergic neuron activity
- Levels of adenosine which builds up during prolonged awakeness (blocked by caffeine)
- Hunger and satiety levels
What abilities are affected during sleep deprivation?
cognitive abilities such as speech production, focusing abilities are impaired (not as much movement impairment)
Which neurons switch REM sleep on and off?
‘on’ switch - acetylcholine cells found in sublateraldorsal nucleus (SLD) in the dorsal pons
‘off’ switch - ventrolateral periaqueductal grey matter (vlPAG) which receive input from arousal systems to keep them active
What effects were observed in sleep deprived rats?
- Increased metabolic rate and weight loss despite increased food intake
- Inability to thermoregulate
- Death after 2-3 weeks
What are the proposed functions of SWS?
- Reduced metabolic rate and blood flow to provide body with rest
- Regions most active during waking have lowest metabolic activity during SWS
- Could protect from free radicals and oxidative stress in the cortex
How does sleep protect the brain?
- cerebrospinal fluid (CSF) penetrates much further into the brain during sleep
- toxic chemicals such as amyloid are removed more quickly during sleep
What is the proposed function of REM sleep?
Reinforcing declarative/non-declarative memory
- People do better in tasks after taking nap with REM
- Place cell sequence replayed during rat sleep, could be consolidating memory
What are the 4 biological rhythms and their time periods?
Ultradian - multiple within 24 hours
Circadian - 24 hours
Infradian - Longer than 24 hours
Circannual - Year long cycle
Which regions of the brain control circadian rhythms?
Lesions to suprachiasmatic nucleus (SCN) disrupts sleep timings.
- Receives input from the retina via light-sensitive ganglion cells
- Region projects indirectly to the VLPA and orexin neurons in the lateral hypothalamus
What proteins control biological rhythms?
7 different proteins such as period (per), cryptochrome (cry) and clock, pulses of light can reset these levels
How does the pinneal gland control seasonal cycles?
By secreting melatonin at night
