Sleep Flashcards
1
Q
What is sleep?
A
recurring, reversible, neurobehavioral state of perceptual disengagement and unresponsiveness to environment
2
Q
Why do we sleep?
A
- Toxin clearance (inc CSF flow), body repair, energy conservation, unlearning/pruning, memory processing, etc
- Sleep deprivation studies show that sleep is important for… learning, emotion integration, psychomotor skills, being alert, maintaining glucose level, immune system function
- Short/disrupted sleep associated w/ obesity, metabolic syndrome, hypertension, depression, earlier death + ACCIDENTS
3
Q
Structures of Wakefulness (5)
A
- 1- Ascending Reticular Activation Center
- Noradrenergic locus coeruleus, serotonergic raphe nuclei, cholinergic nuclei of tegmentum
- From these nuclei signals go to diencephalon and then cortex - wakefulness and arousal
- 2- Tuberomammillary nuclei of posterior hypothalamus
- Histamine (why anti-histamines make you drowsy)
- Activate cortex
- 3- Lateral hypothalamus
- Hypocretin/orexin system (small peptide neuroT that stabilizes sleep-wake transition)
- 4- Basal Forebrain - cholinergic nuclei
- 5- Cerebral Cortex/Limbic System - use glutamate
4
Q
Structures of NREM (4)
A
- 1- Brainstem - sleep facilitating neurons in solitary tract
- 2- VLPO & MnPO of hypothalamus (“sleep switch” ) - active in sleep; turn off wake structure w/ GABA and galaninergic neurons
- 3- Circuits b/n thalamus and cortex - sleep spindles
- 4- Sleep Homeostat - mainly extracellular adenosine in basal forebrain
- Adenosine builds up when awake then decreases after NREM sleep
- Caffeine blocks adenosine receptors
5
Q
Structures of REM (1)
A
Cholinergic & cholinoceptive neurons of PPT and LDT nuclei in pons
6
Q
2 Major Ways Sleep is Regulated
A
- Homeostasis - inc sleep tendency w/ inc # hrs of wakefulness (Process S or sleep drive)
- Circadian Rhythm - 24 hr variation in sleep propensity; drive for sleep is highest at certain parts of day (Process C)
7
Q
Entrainment
A
- Can be entrained (synced to external cues OR zeitgebers such as light)
- Internal Desynchrony - organism forced into length beyond range of entrainment; person may force their sleep/wake cycle to be different so it becomes out of sync w/ other cycles like temp and melatonin
- Bright light in early evening —> delays sleep and circadian is later
- Bright light in early morning —> advances sleep and circadian earlier
8
Q
Ultra-radian v Infra-radian
A
- Ultraradian = cycles < 24 hrs (heart rates)
- Infra-radian = cycles > 24 hrs (period)
9
Q
Where is the anatomical site of our internal clock?
A
suprachiasmatic nuclei (SCN) of hypothalamus
10
Q
Free Running Circadian Rhythm
A
- Endogenous - even w/o environmental stimuli we have cycle
- “Free running” if no environmental time cues; 24.2 hr
11
Q
4 Categories of Sleep Disorders
A
- Insomnia
- Hypersomnia
- Abnormal Behaviors
- Abnormal Timing
12
Q
Sleep Hx and Diary
A
- Hx- pat attention to all meds and recreational substances; 24 hr hx; chronological sequence of their sleep-wake complaints; sleep latency, waking up in night, talk to bed partner
- Sleep Diary - record sleep-wake times, duration of sleep, etc
13
Q
Actinography, PSG, MSLT
A
- Actinography- (FitBit tech) meas patterns of body movement so cannot distinguish REM v NREM but good for sleep rhythm disorders
- Polysomnography - EEG, EOG and EMG; can mess nasal air flow w/ pressure transducer, temp of airflow, chest wall or abdominal wall expansion; arrhythmias, leg movements
- Multiple Step Latency Test (MSLT) - eval daytime sleepiness by having pt in dark room and measuring how long it takes them to fall asleep in middle of day
- Normal = 10-13 min (<8 suggests abnormal sleepiness)
14
Q
Narcolepsy
A
- Impaired sleep-wake control —> daytime sleepiness
- Cataplexy - bilateral loss of vol muscle tone in response to pos emotional stim (transient loss of reflexes) but totally conscious
- Hallucinations right as you’re falling asleep or right as waking up
- Sleep paralysis - complete loss of tone as you wake up
- Type 1 - cataplexy or low CSF hypocretin 1 conc v. Type 2- absence of either
- Low MSLT and transition right into REM sleep
- Cause - dec in hypocretin system in lateral hypothalamus (normally stabilizes sleep-wake transition); possibly autoimmune
- Usually presents in 20s; rare but still .5%
- Tx - stimulants, antidepressants for cataplexy and sleep paralysis; daytime naps; gamma-hydroxybutyrate for cataplexy (“date rape drug”)
15
Q
Obstructive Sleep Apnea
A
- Repeated breathing pauses during sleep b/c airway closes
- Daytime sleepiness, loud snoring, snorts and gasps, poor conc, depression, morning headaches, dry mouth, enuresis
- May be due to obesity, anatomic abnormality, tonsils
- Evidence of diaphragm and chest still moving (v central sleep apnea)
- 4-10% males and 2-5% females; inc w/ age and BMI
- Tx - CPAP or Bi-PAP via nasal mask use pressure to keep airway open; dental device to protrude mandible if mild form; new INSPIRE is hypoglossal nerve stimulation
