Sleep Flashcards
Uses of EEG
. Diagnosis of disease
. Determination of brain death
. Distinguish stages fo sleep
Alpha wave
. Rhythmic waves w/ freq. of 8-13 Hz and moderately low voltage
. Characteristic of awake patients resting quietly
Beta waves
. Lower voltage at higher frequency (14-50 Hz)
. During activation of cortex in awake patient
. Observed primarily when actively concentrating
Theta waves
. Higher voltage w/ freq. of 4-7 Hz
. Mostly recorded in children in parietal and temporal lobes
. Can be seen in adults experiencing frustration and disappointment
. Recorded during stages 2-4 of slow-wave sleep and in bursts during REM
Delta waves
. Very slow (less than 4 Hz) high voltage waves
. Recorded in stage 3 slow-wave sleep and stage 4 slow wave sleep
. Also characteristic of coma
Waking state
. Alpha when relaxed
. Beta when concentrating (beta replaces alpha)
Types fo sleep
Slow-wave sleep
. REM
Stage 1 sleep
. Alpha waves disappear and replaced by low voltage mixed freq. waves
. Thoughts become dissociated but subjects easily aroused by low-intensity stimulation
. Transitional stage btw drowsy but awake and light sleep
Stage 2 sleep
. Light creep
. Low voltage mixed freq. waves
. Occurrence of sleep spindles (short bursts alpha waves) and K complexes (single large biphasic deflections)
Stage 3 sleep
. Deep sleep w/ delta waves w/ freq. less than 2Hz observed 20-50% of time
Stage 4 sleep
. Deep sleep w/ delta waves more than 50% of the time
Eye movement in slow wave deep sleep stages
. Stage 1: slow rolling movement
. 2-4 motionless
. Other skeletal mm. Are active during stages 1-4
REM sleep
. At end of each slaw wave sleep cycle
. Short period where EEG pattern looks similar to wide awake pattern (beta) even through person is dreaming and not awake
. Difficult to arouse person, but a person is more likely to spontaneously wake up in REM that’s other stages
. Rapid eye movements
. Irregular HR and respiration
. Story-like dreaming
New sleep classification system
. Stage W: wakefulness
. Stage N1 and N2: light sleep
. Stage N3: (combines stages 3 and 4): deep sleep
. Stage R: active/REM sleep
. Pattern of cycles called sleep architecture
When are stages 3 and 4 more likely to occur opposed to REM
. 3 and 4 more likely in first few hrs of sleep
. REM more frequent and period is longer late in sleep period (morning hrs)
. If total sleep time is shortened then REM sleep is disproportionately reduced
Age in relation to sleep cycle
. Sleep time dec. w/ age
. Relative percentage of REM vs slow wave dec. from infancy to adulthood
Skeletal mm. Changes during sleep
. activity declines during slow wave sleep
. During REM there is tonic inhibition of skeletal m. Except eye mm. And primary mm. Of respiration
. Period twitches and muscular tremors of face and limbs occur in REM when periodic bursts of excitatory activity break through generalized tonic inhibition
Cardiovascular and respiratory system during sleep cycle
. Slow wave sleep has steady dec. in bp, HR, and RR
. REM has inc. and large oscillations in bp, HR, and RR
. Very high phasic bps in REM assoc. w/ strokes and heart attacks
. Fatal heart attacks most common from 5-6am when most people are in REM sleep
Growth hormone in children sleep cycle
. Secreted exclusively during sleep
. Peaks during early portion of sleep period (non-REM stages 3 and 4)
. In adolescence and puberty it is still mostly at night but there are also peaks throughout the day
Prolactin in sleep
. Secretion occurs almost entirely during sleep
. Maximal in morning hours
Cortisol during sleep
. Reaches its minimum early in sleep and peaks at end of sleep period
TSH secretion during sleep
. Peaks prior to onset of sleep and then declines during sleep
Luteinizing hormone during sleep
. Drives testosterone production
. Inc. during sleep responsible for meal puberty
. LH secretion in adult males is less related to sleep
Follicle stimulating hormone in sleep
. Follows similar pattern to LH
. During female puberty it peaks during sleep
Body temp during sleep
. As night progresses core Body temp drops reaching minimum during slow wave sleep. In early morning hrs
. During REM body temp. Inc. slightly
Renal function changes during sleep
. Dec. urine volume
. Inc. osmolality
Functions of slow wave sleep
. May serve as time for body rest and metabolic restoration
REM sleep functions
. Needed for physical changed necessary for long-term memory and learning
Circadian rhythm cycle
8 hr sleep
16 hr awake
Suprachiasmatic nucleus of hypothalamus
. Basic circadian rhythm
. Inputs from retina modulate it
. Jet lag and sleep problems assoc. W/ working alternating shifts dur to confusion of visual cues
. Interacting pos. And neg. feedback loops that regulate gene expression are central to setting basic circadian rhythm
Arousal systems in brain
. Cholinergic neurons in upper pons activate thalamic nuclei and adrenergic neurons in upper brainstem to stimulate cerebral cortex
. Peptidergic neurons in hypothalamus contain orexins and melanin concentrating hormone to stimulate cerebral cortex and brainstem arousal areas
Arousal system in brainstem
. Raphe nuclei
. Part of reticular activating system that sets general level of arousal
. Amphetamines act here to promote arousal and dec. sleep
. Excitatory neurons in reticular activating system are active during working state and lead to arousal and enhanced attention to outside word
Sleep systems in hypothalamus
. Inhibitory GABA-containing neurons in preoptic nucleus of hypothalamus inhibit arousal areas of brainstem
. Orexin-containing neurons in lat. hypothalamus activate arousal areas
. His-containing neurons in post. Hypothalamus project to reticular activating system and promote wakefulness
. Drowsiness assoc. w/ anti-histamines due to inhibition of histaminergic neurons
REM-promoting areas of brain
. Pontine tegmentum
. Ventrolat. Periaqueductal gray matter
Sleep-promoting peptides
. VIP and delta sleep inducing peptide (DSIP) inducing delta waves
. DSIP does not initiate sleep but keep sleep/wake cycle in proper order
Sleep-inhibiting peptides
Orexins/hypocretins
. Released from neurons whose cell bodies are in lat. hypothalamus but axons project throughout brain
. Similar to GI hormone secretin
. Activate thalamic nuclei and stimulate cerebral cortex and brainstem around areas
Cytokines and sleep
.lipopolysaccharide
. IL-1
. Interferon-alpha-2
. TNF
Cholecystokinin (CCK) and sleep
. Contributes to drowsiness assoc. w/ large meal
ADH and sleep
May promote REM sleep
Melatonin
. Secreted by pineal gland
. Acts on suprachiasmatic nucleus via specific receptors that lead to gene transcription of proteins involved in circadian rhythm
. Useful treatment of jet lag and insomnia in elderly but not as general sleeping pill
Insomnia
, difficulty falling asleep, awakening frequently, waking up early and not being able to get back to sleep
. Waking up feeling unrefreshed
. Caused by stress, anxiety, caffeine
Disorders of excessive somnolence (DOES)
. Most common is narcolepsy
. Chronically sleepy during day
. Often have abnormal tendency to progress suddenly from being awake to REM sleep in response to emotional stimulus
. Abnormal REM sleep accompanied by cataplexy (loss of mm. Tone/paralysis)
. Assoc. w/ loss of hypocretin producing cells in hypothalamus
Dysomnias
. Disturbances of normal circadian rhythmicity of sleep
. Jet lag is reduced after a 16 hr fast
Parasomnias
. Normally undesirable behaviors that occur exclusively during sleep or are exaggerated by sleep
Night terrors
. Certain types of dreams occurring during slow wave sleep characterized by feelings as opposed to specific images
. Most common in kids 3-5
. Child will waken abruptly, scream and run about disoriented unable to speak coherently, then go back to sleep after 3-4 minutes
Sleepwalking
. Complex motor behaviors while person is in slow wave sleep
. Eyes are open and person appears awake
REM sleep disorder
. Person acts out dreams during sleep when they are normal paralyzed
. Dreams usually frightening and are. Accompanied by violent behavior
Pseudoinsomnia (sleep state misperception)
. Person sleeps adequately but dreams about not being asleep
. Wake up tired w/ dark eye circles
Obstructive sleep apnea
. Physical blockage of airway due to collapse of soft tissue in rear of through
. Assoc. w/ obesity and snoring
Central sleep apnea
. Rare
. Skeletal m. Inhibition during REM extends to inhibition of respiratory mm.
. Lead to inc. risk of high bp, stroke, and heart attack
. Can be turreted w/ CPAP or surgery
. Weight loss can be effective long-term solution
Restless leg syndrome and periodic limb movement disorder
. Pins and needles, itchiness, or creeping crawling sensations leading to vigorous movement of legs esp. around bedtime
. Awakens sleeper during sleep
. PLMD consists of repetitive movement of toe, foot, knee, or hip during sleep that can also lead to awakening
. Treatment if severe: dopaminergic agonists, benzos, or opioids
Effects of sleep deprivation
. Inc. incidence of hypertension, weight gain, periodontal disease, and suicide
. Acute deprivation leads to cognitive decline, mood swings, and depression
Sleep promoting pharmacology
. Alcohol due to relaxation
. Hypnotics
. Anti-histamines
. DSIP
Sleep inhibiting drugs
. Caffeine
. Meds (steroids, opiates can cause sleep apnea, vit. B)
. Cocaine: suppresses REM sleep
. Newer narcolepsy drugs: stimulants modafinil and armodafinil
