Sleep Flashcards
How often does the sleep cycle occur each night?
4-5 times
Subsequent cycles decreased slow wave, increase rem
What are the stages of sleep?
Awake
Drowsy
NREM:
50% theta rhythms
Theta with burst k complexes and spindles
Slow wave/deep sleep, delta waves (synchrony)
REM
Low amplitude, desynchronised eeg
Looks like youre awake
Limbs relaxed
Why are minor awakenings in sleep cycle important?
Prevents nerve compression
Prevents circulatory pooling
Looks for threats
What are the sleep pathways/brain areas involved in sleep?
Ascending reticular activating system Ventrolateral preoptic area Superchiasmic nucleus Orexin/hypocretin system Pontine tegmentum
Describe the ascending reticular activating system
Thalamus to cortex
Uses ne, 5ht, da and hist to INCREASE WAKEFULLNESS
Describe the role of ventrolateral pre-optic area
Portion of the anterior hypothalamus
Active during nonREM
Releases gaba and galanin inhibiting neurones involved in wakefullness
Activated by 5ht and adenosine
Describe role of superchiasmic nucleus
Controls circadian rhythms
Input from retina
Projections to hypothal nuc and pineal gland to control body temp and cortisol levels
Describe the orexin/hypocretin system
Lateral hypothal
Orexin is a neuropeptide that binds gpcr
Involved in sleep, feeding behaviour, sexual activity
Promotes wakefullness, excites monoaminergic neurones of ARAS
Inhibited by vlpo neurones during nrem
Integrates external stimuli to determine wakefullness
Discuss narcolepsy
Mutation in orexin receptor causes narcolepsy in dogs
Some narcoleptic people have orexin peptide deficiency
Abnormal transition between rem and nonrem at night and sleep wake cycle
Intrusive episodes of rem
Hallucination at onset of sleep
Discuss pontine tegmentum
Drives rem
Contains drugs to turn rem on and off
Produces eye movement and muscle atonia
What determines sleep?
Homeostatic controls
Sleep modulating substances
Adenosine
Circadian rhythms
How do homeostatic control sleep?
Poorly understood
Inversely correlates w/ amount of prior slow wave sleep
Name sleep modulating substances
Muramyl dipeptide Interleukin-1 Delta-sleep inducing peptide Prostaglandin p2 Tumour necrosis factor
Role of adenosine
Increases during prolonged wakefullness
Decreased at awakening
Inhibits monominergic input to aras
Adenosine r knockout mouse showed adenosine does not induce sleep alone
Circadian rhythms
Endogenously driven 24hr cycle of bioactivity
Helps organism cope w/ changes in environment
Controlled by scn neurones
Maintained by expression of period genes and cryptochrome genes
Protein products increase during waking hours
Scn neurones have photoreceptors
Insomnia
Difficulty initiating and maintaining sleep
Hypersomnia
Sleep longer during day and have greater propensity to fall asleep
Sleep apnea
Nasopharyngeal collapse during sleep, snoring
Causes cardiac and pulmonary arrhythmias
Benzodiazepines
Lower risk over overdose compared to barbs
Anxiolytic and promotes onset of sleep
Increase gabaa r affinity for endogenous gaba
Increases opening time of cl channel
Triazolam
Benzodiazepine
Short half life promotes onset of sleep
Rebound insomnia
Flurazepam
Long half life interfers with day time activity
Benzo
Estazolam
Benzo
Some daytime sedation
Tenazepam
Benzo
Good but daytime sedation
Zolpidem
Not benzo but acts on same site
