Sleep Flashcards
What are electrooculograms and electromyograms used for?
Electrooculogram: measures eye movement
Electromyogram: measures facial muscle contraction/movement
Table compaing rate of brain activity, hertz, rhythm and muscle activity for each stage of sleep
(awake, NREM 1-2, NREM 3-4, REM).
What happens to HR and RR during REM sleep?
increased.
Outline the sleep cycle.
Cycle consists of NREM1-4 and REM sleep. Last 1-1.5 hours. Repeats.
ECG rhythm slows up to stage 4 and transitions to rapid rhythms in REM.
How does sleep change as the night progresses?
more slow wave sleep at the beginning of the night and more REM at the end
How does sleep regulation change with sleep deprivation?
More REM sleep
More slow wave sleep
Sleep onset is earlier
Sleep for longer
How does the RAS control consciousness?
Projects into cerebral cortex from brainstem to influence its activity.
Higher activity –> higher arousal
How does the RAS act both directly and indirectly?
Direct influence: directly synapses in the cerebral cortex
Indirect: uses intralaminar nuclei of the thalamus
What is the role of the lateral hypothalamus?
How does it do this?
promotes wakefulness - excitatory stimulation of RAS using orexin
active during day
What is the role of the ventrolateral preoptic nucleus? how does it do this?
Promote sleep.
Inhibits RAS.
Active during day.
Explain the relationship between the lateral hypothalamus and the ventrolateral preoptic nucleus.
antagonistic, so activation of one inhibits the other (LH active at start of day and VLP at end
What is the role of the suprachiasmatic nucleus?
synchronise sleep with falling light level.
How does the SC nucleus function?
receives input from ganglion cells in retina, and as light levels fall, SC nucleus becomes more active, activating hypothalamic nuclei to inhibit the LH and stimulate the VLP nucleus
Where is the pineal gland located?
back of the third ventricle.
What does the pineal gland secrete? What does this hormone do?
melatonin.
Modulate sleep.
What are the functions of sleep?
Restoration/recovery
Energy conservation
Predator avoidance
Specific brain functions
What are the functions of dreaming?
Safety valve for antisocial emotion
Disposal of unimportant/unwanted memories
Memory consolidation (NREM sleep = declarative memory [facts/events], REM sleep = procedural memory [skills])
compare dreaming in NREM and REM sleep.
REM - more frequent and well recalled.
Outline the psychiatric, neurological and somatic effects of sleep deprivation.
Psychiatric: tiredness, stress, mood fluctuations and depression
Neurological: impaired attention, risk of errors, neurodegeneration
Somatic: glucose intolerance, impaired immunity, reduced leptin/increased appetite
How is insomnia treated?
removing cause, improving sleep routine and using hypnotic drugs (to enhance inhibitory GABAergic circuits)
Give some potential causes of insomnia.
pain/apnoea, brain dysfunction, depression, night working.
List some primary causes of hypersomnia
narcolepsy, post TBI, idiopathic
List some secondary causes of hypersomnia.
Due to poor overnight sleep:
Obstructive sleep apnoea
Nocturnal pain
Anxiety
Medication
Restless legs syndrome
What is narcolepsy?
falling asleep repeatedly during day with disturbed overnight sleep, with cataplexy (sudden loss of voluntary muscle tone triggered by strong emotions)
What is narcolepsy associated with?
dysfunction of REM sleep due to orexin deficiency
What is orexin? Why might it be deficient? How is deficiency managed?
lateral hypothalamic neurotransmitter.
Deficiency due to genetic/autoimmune deficiency
Manage with strict sleep routines.
