sleep & circadian rhythms

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SLEEP & CIRCADIAN SLEEP & CIRCADIAN RHYTHMS RHYTHMS Images in these slides were obtained from the following sources: Carlson, Physiology of Behavior, 9 th edition (2007) Allyn and Bacon

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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 Presentation

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Page 1: SLEEP & CIRCADIAN RHYTHMS

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

Page 2: SLEEP & CIRCADIAN RHYTHMS

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

Page 3: SLEEP & CIRCADIAN RHYTHMS

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

Page 4: SLEEP & CIRCADIAN RHYTHMS

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)

Page 5: SLEEP & CIRCADIAN RHYTHMS

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”

Page 6: SLEEP & CIRCADIAN RHYTHMS

SWS VS. REM SLEEPSWS VS. REM SLEEP

Page 7: SLEEP & CIRCADIAN RHYTHMS

SLEEP CYCLESSLEEP CYCLES

Page 8: SLEEP & CIRCADIAN RHYTHMS

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

Page 9: SLEEP & CIRCADIAN RHYTHMS

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.

Page 10: SLEEP & CIRCADIAN RHYTHMS

LIFE SPAN LIFE SPAN CHANGES IN SLEEPCHANGES IN SLEEP

Page 11: SLEEP & CIRCADIAN RHYTHMS

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)

Page 12: SLEEP & CIRCADIAN RHYTHMS

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)

Page 13: SLEEP & CIRCADIAN RHYTHMS

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

Page 14: SLEEP & CIRCADIAN RHYTHMS

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.

Page 15: SLEEP & CIRCADIAN RHYTHMS

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

Page 16: SLEEP & CIRCADIAN RHYTHMS

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)

Page 17: SLEEP & CIRCADIAN RHYTHMS

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

Page 18: SLEEP & CIRCADIAN RHYTHMS

COMPARATIVE STUDIES COMPARATIVE STUDIES OF SLEEPOF SLEEP

Page 19: SLEEP & CIRCADIAN RHYTHMS

SLEEP IN MARINE SLEEP IN MARINE MAMMALSMAMMALS

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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

Page 21: SLEEP & CIRCADIAN RHYTHMS

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”

Page 22: SLEEP & CIRCADIAN RHYTHMS

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.

Page 23: SLEEP & CIRCADIAN RHYTHMS

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.

Page 24: SLEEP & CIRCADIAN RHYTHMS

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.

Page 25: SLEEP & CIRCADIAN RHYTHMS

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.

Page 26: SLEEP & CIRCADIAN RHYTHMS

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

Page 27: SLEEP & CIRCADIAN RHYTHMS

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

Page 28: SLEEP & CIRCADIAN RHYTHMS

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

Page 29: SLEEP & CIRCADIAN RHYTHMS

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

Page 30: SLEEP & CIRCADIAN RHYTHMS

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

Page 31: SLEEP & CIRCADIAN RHYTHMS

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

Page 32: SLEEP & CIRCADIAN RHYTHMS

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

Page 33: SLEEP & CIRCADIAN RHYTHMS

NEUROTRANSMITTERS NEUROTRANSMITTERS AND SLEEPAND SLEEP

Page 34: SLEEP & CIRCADIAN RHYTHMS

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

Page 35: SLEEP & CIRCADIAN RHYTHMS

LABORATORY STUDIES OF LABORATORY STUDIES OF CIRCADIAN RHYTHMSCIRCADIAN RHYTHMS

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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

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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.

Page 38: SLEEP & CIRCADIAN RHYTHMS

NEURAL MECHANISMSNEURAL MECHANISMSOF CIRCADIAN OF CIRCADIAN

RHYTHMSRHYTHMS

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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

Page 40: SLEEP & CIRCADIAN RHYTHMS

SUPRACHIASMATIC SUPRACHIASMATIC NUCLEUSNUCLEUS