sleep & circadian rhythms
DESCRIPTION
SLEEP & CIRCADIAN RHYTHMS. Images in these slides were obtained from the following sources: Carlson, Physiology of Behavior, 9 th edition (2007) Allyn and Bacon Rosenzweig, Leiman and Breedlove, Biological Psychology (2001) Sinaur Associates, Inc. SLEEP PHYSIOLOGY. PHYSIOLOGICAL MEASURES - PowerPoint PPT PresentationTRANSCRIPT
SLEEP & SLEEP & CIRCADIAN CIRCADIAN RHYTHMSRHYTHMS
Images in these slides were obtained from the following sources:Carlson, Physiology of Behavior, 9th edition (2007) Allyn and BaconRosenzweig, Leiman and Breedlove, Biological Psychology (2001) Sinaur Associates, Inc
SLEEP PHYSIOLOGYSLEEP PHYSIOLOGY
PHYSIOLOGICAL MEASURESPHYSIOLOGICAL MEASURES Electroencephalogram (EEG)Electroencephalogram (EEG)
brain waves from scalp surfacebrain waves from scalp surface Electrooculogram (EOG)Electrooculogram (EOG)
eye movementseye movements Electromyogram (EMG)Electromyogram (EMG)
muscle tonemuscle tone
SLEEP PHYSIOLOGY SLEEP PHYSIOLOGY EEG Waves (wakefulness)EEG Waves (wakefulness)
beta wavesbeta waves Irregular low amp., high freq. waves Irregular low amp., high freq. waves
(13-30 Hz)(13-30 Hz) indicative of alert and vigilant activityindicative of alert and vigilant activity
alpha wavesalpha waves regular medium freq. waves (8-12 Hz)regular medium freq. waves (8-12 Hz) resting quietly, but awakeresting quietly, but awake
SLEEP PHYSIOLOGYSLEEP PHYSIOLOGY SLEEP STAGESSLEEP STAGES
Stage 1: alpha and Stage 1: alpha and theta waves (initial)theta waves (initial)
Stage 2: K complexes, Stage 2: K complexes, sleep spindlessleep spindles
Stage 3: 20-50% delta Stage 3: 20-50% delta (SWS)(SWS)
Stage 4: > 50% delta Stage 4: > 50% delta (SWS)(SWS)
REM (emergent stage REM (emergent stage 1)1)
SLEEP PHYSIOLOGYSLEEP PHYSIOLOGY REM SLEEPREM SLEEP
increased cerebral activity, erratic EEG increased cerebral activity, erratic EEG (beta and theta waves)(beta and theta waves)
rapid eye movementsrapid eye movements loss of core muscle tone (paralysis)loss of core muscle tone (paralysis) autonomic arousal (elevated hr, bp, and autonomic arousal (elevated hr, bp, and
respiration)respiration) narrative dreams with much visual imagerynarrative dreams with much visual imagery
initially referred to as initially referred to as “PARADOXICAL SLEEP”“PARADOXICAL SLEEP”
SWS VS. REM SLEEPSWS VS. REM SLEEP
SLEEP CYCLESSLEEP CYCLES
SLEEP PATTERNSSLEEP PATTERNS Percent of SWS vs. REM changes with Percent of SWS vs. REM changes with
ageage Young Adult sleep patterns consist of:Young Adult sleep patterns consist of:
7-8 hours of 90-110 min. repeating cycles7-8 hours of 90-110 min. repeating cycles 45-50% of total sleep is stage 245-50% of total sleep is stage 2 20% of total sleep is REM sleep20% of total sleep is REM sleep More SWS early in nightMore SWS early in night Progressive lengthening of REM periodsProgressive lengthening of REM periods
LIFE SPAN LIFE SPAN CHANGES IN SLEEPCHANGES IN SLEEP
Daily sleep rhythms begin ~ 16 weeks.Daily sleep rhythms begin ~ 16 weeks. Greater % REM in infants and children.Greater % REM in infants and children. REM component decreases with age.REM component decreases with age. Total sleep time decreases with age.Total sleep time decreases with age. Elderly frequently experience insomnia Elderly frequently experience insomnia
and decreased SWS.and decreased SWS.
LIFE SPAN LIFE SPAN CHANGES IN SLEEPCHANGES IN SLEEP
SLEEP DISORDERSSLEEP DISORDERS INSOMNIAINSOMNIA
affects ~25% of population affects ~25% of population occasionally, ~9% regularlyoccasionally, ~9% regularly
No single definitionNo single definition Insomnia is symptom, not a diseaseInsomnia is symptom, not a disease multiple causes, often iatrogenicmultiple causes, often iatrogenic
tolerance to sedative-hypnotic drugstolerance to sedative-hypnotic drugs frequent symptom of depressionfrequent symptom of depression Other causes: sleep apnea, nocturnal Other causes: sleep apnea, nocturnal
myoclonus, restless legs (PLMD)myoclonus, restless legs (PLMD)
SLEEP DISORDERSSLEEP DISORDERS Sleep-onset insomniaSleep-onset insomnia
difficulties falling asleepdifficulties falling asleep
Sleep maintenance insomniaSleep maintenance insomnia frequent awakenings, may be frequent awakenings, may be
associated with SLEEP APNEA associated with SLEEP APNEA (difficulty breathing while (difficulty breathing while asleep)asleep)
SLEEP DISORDERSSLEEP DISORDERSNARCOLEPSYNARCOLEPSY
Characteristic Symptoms:Characteristic Symptoms: Sleep Attack (5-30 minutes)Sleep Attack (5-30 minutes) CataplexyCataplexy
frequently brought on by intense emotionsfrequently brought on by intense emotions
Immediate REM at sleep onsetImmediate REM at sleep onset Sleep ParalysisSleep Paralysis Hypnogogic HallucinationsHypnogogic Hallucinations
SLEEP DISORDERSSLEEP DISORDERS NARCOLEPSYNARCOLEPSY
Heritability and Hypocretin (Orexin)Heritability and Hypocretin (Orexin) Genetic models in dogsGenetic models in dogs
increased ACh receptors in pons increased ACh receptors in pons amygdala and forebrain degenerationamygdala and forebrain degeneration canarccanarc gene (Hypocretin 2 receptors) gene (Hypocretin 2 receptors)
Hypocretin gene knockout mouse modelHypocretin gene knockout mouse model CSF analysis in human narcoleptic patients CSF analysis in human narcoleptic patients
show diminished hypocretin levels.show diminished hypocretin levels.
SLEEP DISORDERSSLEEP DISORDERS
REM SLEEP BEHAVIOR DISORDERREM SLEEP BEHAVIOR DISORDER Characterized by failure to exhibit muscle Characterized by failure to exhibit muscle
paralysis during REM sleepparalysis during REM sleep Appears to be neurodegenerative disorder Appears to be neurodegenerative disorder
with some possible genetic componentwith some possible genetic component Often associated with other neurodegenerative Often associated with other neurodegenerative
disorders, such as Parkinson’s diseasedisorders, such as Parkinson’s disease Usually treated with clonazepam, a Usually treated with clonazepam, a
benzodiazepinebenzodiazepine
SLEEP DISORDERSSLEEP DISORDERS COMMON CHILDHOOD COMMON CHILDHOOD
SLEEP DISORDERS SLEEP DISORDERS ASSOSCIATED WITH SLOW ASSOSCIATED WITH SLOW WAVE SLEEPWAVE SLEEP Pavor Nocturnus (night terrors) Pavor Nocturnus (night terrors) Somnambulism (sleep walking)Somnambulism (sleep walking) Nocturnal Enuresis (bed Nocturnal Enuresis (bed
wetting)wetting)
SLEEP FUNCTIONSSLEEP FUNCTIONS(Why do we sleep?)(Why do we sleep?)
Restorative FunctionsRestorative Functions growth and repairgrowth and repair
Adaptive FunctionsAdaptive Functions predator avoidancepredator avoidance energy conservationenergy conservation
Cognitive FunctionsCognitive Functions learning, unlearning, learning, unlearning,
reorganizationreorganization
COMPARATIVE STUDIES COMPARATIVE STUDIES OF SLEEPOF SLEEP
SLEEP IN MARINE SLEEP IN MARINE MAMMALSMAMMALS
SLEEP SLEEP DEPRIVATIONDEPRIVATION
Early reports of bizarre or psychotic Early reports of bizarre or psychotic behaviorbehavior
Wide individual variability (personality Wide individual variability (personality and age factors)and age factors)
Most common effects of sleep Most common effects of sleep deprivation:deprivation: increased irritabilityincreased irritability decreased concentrationdecreased concentration Confusion/disorientationConfusion/disorientation
SLEEP DEPRIVATION SLEEP DEPRIVATION IN HUMANSIN HUMANS
Performance on brief tasks is unimpaired.Performance on brief tasks is unimpaired. Performance on tasks that involve high Performance on tasks that involve high
motivation are generally not impaired.motivation are generally not impaired. Sleep Recovery (Randy Gardner story)Sleep Recovery (Randy Gardner story)
11 days (264 hours) sleep deprivation11 days (264 hours) sleep deprivation 1st night, ~ 15 hours; stage 4 increased at expense of 1st night, ~ 15 hours; stage 4 increased at expense of
stage 2stage 2 2nd night, ~10 hours; greatest REM recovery2nd night, ~10 hours; greatest REM recovery Percentages of sleep recovery not equivalent across Percentages of sleep recovery not equivalent across
all stages: 7% of stages 1 and 2, 68% SWS, 53% REM all stages: 7% of stages 1 and 2, 68% SWS, 53% REM sleep “made up”sleep “made up”
SLEEP DEPRIVATION IN SLEEP DEPRIVATION IN NONHUMANSNONHUMANS
It is difficult to tease apart effects of sleep It is difficult to tease apart effects of sleep deprivation versus stressful effects of the deprivation versus stressful effects of the procedure.procedure.
Rechtschaffen and Bergmann, 1995Rechtschaffen and Bergmann, 1995 Carousel apparatus with yoked controlsCarousel apparatus with yoked controls Experimental animals died within days, Experimental animals died within days,
while controls remained relatively healthy.while controls remained relatively healthy.
EFFECTS OF ACTIVITIES EFFECTS OF ACTIVITIES ON SLEEPON SLEEP
Effects of Exercise on SleepEffects of Exercise on Sleep Does the brain recover from day time Does the brain recover from day time
physical exertion?physical exertion? Little compelling evidence: People who Little compelling evidence: People who
spend much of their time resting in bed spend much of their time resting in bed do not sleep lessdo not sleep less
Effects of Mental Activity on SleepEffects of Mental Activity on Sleep Does the brain recover from day time Does the brain recover from day time
mental exertion?mental exertion? Some studies have shown that extensive Some studies have shown that extensive
mental activities are followed by normal mental activities are followed by normal sleep duration, but increased SWS.sleep duration, but increased SWS.
FUNCTIONS OF REM FUNCTIONS OF REM SLEEPSLEEP
Theories that REM sleep is required for Theories that REM sleep is required for normalnormal Mental healthMental health MotivationMotivation Cognitive processingCognitive processing
Interesting links between REM sleep Interesting links between REM sleep and depressionand depression REM deprivation has antidepressant effectsREM deprivation has antidepressant effects Most antidepressant drugs also reduce REM Most antidepressant drugs also reduce REM
sleep.sleep. There’s considerable research on links There’s considerable research on links
between REM sleep and between REM sleep and learning/memory.learning/memory.
REM SLEEP REM SLEEP DEPRIVATIONDEPRIVATION Following REM deprivation, there is a Following REM deprivation, there is a
compensatory increase in REM sleep, compensatory increase in REM sleep, which seems to suggest REM sleep is a which seems to suggest REM sleep is a necessary brain function.necessary brain function.
Some evidence that REM deprivation Some evidence that REM deprivation can produce cognitive/memory deficits.can produce cognitive/memory deficits.
Some evidence that REM sleep Some evidence that REM sleep increases following new learning.increases following new learning.
NEURAL NEURAL MECHANISMS OF MECHANISMS OF
SLEEPSLEEP
Basal ForebrainBasal Forebrain Brain Stem Reticular Brain Stem Reticular
FormationFormation Raphe nucleus (midbrain)Raphe nucleus (midbrain) Locus Coeruleus (pons)Locus Coeruleus (pons) Lateral hypothalamusLateral hypothalamus
NEURAL NEURAL MECHANISMS OF MECHANISMS OF
SLEEPSLEEP Sleep is an active state Sleep is an active state
mediated by at least three mediated by at least three neural systemsneural systems Forebrain: generates SWSForebrain: generates SWS Reticular Formation: Wakes Reticular Formation: Wakes
ForebrainForebrain Pons: Triggers REM sleepPons: Triggers REM sleep
NEURAL NEURAL MECHANISMS OF MECHANISMS OF
SLEEPSLEEP Bremer (1935)Bremer (1935)
Encephale isoleEncephale isole Cerveau isoleCerveau isole
Moruzzi and Moruzzi and Magoun (1949)Magoun (1949) Reticular Reticular
formationformation Jouvet (1967)Jouvet (1967)
Raphe systemRaphe system
NEURAL NEURAL MECHANISMS OF MECHANISMS OF
SLEEPSLEEP
BASAL FOREBRAINBASAL FOREBRAIN ventral frontal lobe, anterior ventral frontal lobe, anterior
hypothalamushypothalamus lesions abolish SWSlesions abolish SWS electrical or heat stimulation can electrical or heat stimulation can
induce SWS activityinduce SWS activity These neurons are active at sleep These neurons are active at sleep
onsetonset Inhibited by NE stimulationInhibited by NE stimulation
NEURAL NEURAL MECHANISMS OF MECHANISMS OF
SLEEPSLEEP RETICULAR RETICULAR
FORMATIONFORMATION central core of brain stemcentral core of brain stem diffuse group of cells diffuse group of cells
extending from medulla to extending from medulla to thalamusthalamus
electrical stimulation electrical stimulation produces arousal, awakens produces arousal, awakens a sleeping animala sleeping animal
lesions produce persistent lesions produce persistent sleepsleep
NEURAL NEURAL MECHANISMS OF MECHANISMS OF
SLEEPSLEEP RAPHE NUCLEIRAPHE NUCLEI
A system of serotonergic A system of serotonergic neurons along midline of neurons along midline of brain stem.brain stem.
Lesions to Raphe nuclei Lesions to Raphe nuclei produce insomnia.produce insomnia.
PCPA inhibits 5-HT PCPA inhibits 5-HT synthesis and reduces synthesis and reduces sleep, whereas 5-HT sleep, whereas 5-HT agonists promote sleep agonists promote sleep
NEURAL NEURAL MECHANISMS OF MECHANISMS OF
SLEEPSLEEP
PONSPONS crucial for REM sleep componentscrucial for REM sleep components lesions ventral to Locus Coeruleus lesions ventral to Locus Coeruleus
abolish REM sleepabolish REM sleep electrical or pharmacological electrical or pharmacological
stimulation (ACh agonists) can stimulation (ACh agonists) can induce or prolong REM sleepinduce or prolong REM sleep
small lesions ventral to LC selectively small lesions ventral to LC selectively abolish REM muscle atoniaabolish REM muscle atonia
NEUROTRANSMITTERS NEUROTRANSMITTERS AND SLEEPAND SLEEP
CIRCADIAN CIRCADIAN RHYTHMSRHYTHMS
DEFINITIONDEFINITION 24 hr. endogenous cycles24 hr. endogenous cycles
EXAMPLESEXAMPLES sleep/wake cyclesleep/wake cycle body temperaturebody temperature hormone secretionhormone secretion drug sensitivitydrug sensitivity
LABORATORY STUDIES OF LABORATORY STUDIES OF CIRCADIAN RHYTHMSCIRCADIAN RHYTHMS
CIRCADIAN CIRCADIAN RHYTHMSRHYTHMS
TERMINOLOGYTERMINOLOGY Free Running PeriodFree Running Period EntrainmentEntrainment ZeitgeberZeitgeber Phase ShiftsPhase Shifts
phase advances: phase advances: acceleration of circadian acceleration of circadian rhythmrhythm
phase delays: deceleration phase delays: deceleration of circadian rhythmof circadian rhythm
CIRCADIAN CIRCADIAN RHYTHMSRHYTHMS
Circadian Timing MechanismsCircadian Timing Mechanisms Internal desynchronization of S-W cycle and Internal desynchronization of S-W cycle and
body temp. cycle suggest separate timing body temp. cycle suggest separate timing mechanisms.mechanisms.
Common Examples of Phase ShiftsCommon Examples of Phase Shifts Jet Lag results from phase shifts in circadian Jet Lag results from phase shifts in circadian
rhythms as a result of traveling across time rhythms as a result of traveling across time zones.zones.
Shift workers often forced to adjust S-W Shift workers often forced to adjust S-W cycle. Such disruptions may affect health cycle. Such disruptions may affect health and productivity.and productivity.
NEURAL MECHANISMSNEURAL MECHANISMSOF CIRCADIAN OF CIRCADIAN
RHYTHMSRHYTHMS
SUPRACHIASMATIC SUPRACHIASMATIC NUCLEUSNUCLEUS
Experimental Research on SCN Experimental Research on SCN involvement in circadian rhythmsinvolvement in circadian rhythms
Large lesions of hypothalamus disrupt Large lesions of hypothalamus disrupt circadian cycles of activity in rats. (Richter, circadian cycles of activity in rats. (Richter, 1967)1967)
Lesions specific to SCN disrupt periodicity Lesions specific to SCN disrupt periodicity of sleep/wake cycleof sleep/wake cycle
SCN displays circadian cycles of SCN displays circadian cycles of electrical, metabolic, and electrical, metabolic, and biochemical activity.biochemical activity.
Fetal tissue transplants in hamsters Fetal tissue transplants in hamsters Fetal tissue from 20 hour donor implanted in 25 Fetal tissue from 20 hour donor implanted in 25
hour recipient after SCN lesion. hour recipient after SCN lesion. Recipient becomes entrained to 20 hour cycle Recipient becomes entrained to 20 hour cycle
SUPRACHIASMATIC SUPRACHIASMATIC NUCLEUSNUCLEUS