Transcript Overview of Sleep

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OVERVIEW OF SLEEP
RITU G. GREWAL, MD
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Key to Evaluation of Sleep Problems
• Sleep Physiology
• Factors that impact on sleep
• Sleep History
• Polysomnogram
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Defining Sleep
• Sleep physicians define human sleep on the basis of a
person’s observed behavior (reclined position, closed
eyes, decreased movement, decreased responsivness to
stimuli)
• and accompanying physiologic changes in brain’s
electrical activity
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SLEEP  REST
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Differentiating Sleepiness from Tiredness
or Fatigue
• A tired or fatigued individual does not necessarily have a
propensity to fall asleep given an opportunity to do so.
• A sleepy individual is not only anergic but will fall asleep
given the opportunity to do so.
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Responsiveness to Stimuli is Not
Completely Absent in Sleep
• a sleeper continues to process some sensory
information during sleep
• meaningful stimuli are more likely to produce arousals
than non-meaningful ones
• sound of one’s own name is more likely to arouse than other
sounds
• cry of her baby is more likely to arouse a sleeping mother than
a cry of another infant.
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Sleep
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Active
Complex
Highly Regulated
Involves different neuronal groups
Purpose is not understood
Essential
Composed of two fundamentally different states : REM
sleep & NREM sleep
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Sleep consists of two strikingly different
states
• non-rapid eye movement sleep (NREM)
• “shallow” NREM stage 1 (start of sleep)
• “deeper” NREM stages 2
• “deepest”3 (slow wave sleep)
• brain is regulating bodily functions in a movable body
• rapid eye movement sleep (REM)
• highly activated brain in a paralyzed body
• first brief episode of REM follows NREM in
approximately 90 minutes
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Normal Sleep Histogram
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How Much Sleep Does One Need?
• One needs sufficient sleep to feel alert, refreshed, and
avoid falling asleep involuntarily during the waking
hours.
• Most young adults average between 7 and 8 hours of
sleep nightly, but there is a significant individual and
night to night variability
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Three States of Being
• Wake
• REM Sleep
• Non-REM Sleep
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• The Cyclic alteration of these three states defines two
sleep rhythms
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CIRCADIAN RHYTHM
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ULTRADIAN RHYTHM
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Two Drives Regulating Sleep
• Sleep is regulated by the two basic processes:
• homeostatic process, which depends on the amount
of prior sleep and wakefulness
• circadian process, which is driven by an
endogenous circadian pacemaker, generating near
24-hour cycles of behavior.
• The interaction of homeostatic and circadian
processes helps to maintain wakefulness
during the day and consolidated sleep at night
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Homeostatic Factor
• Virtually all organisms have an absolute need to sleep.
• Humans cannot remain awake voluntarily for longer
than two – three days
• rodents cannot survive without sleep for longer than
few weeks.
• The homeostatic factor represents an increase in the
need for sleep, “sleep pressure”, with increasing
duration of prior wakefulness.
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Homeostatic Regulation of Sleep
• When normal sleep is preserved,
• homeostatic factor represents a basic increase in
sleep propensity during waking hours
• When a normal amount of sleep is reduced,
• the homeostatic drive is increased
• leading to increased sleep pressure and sleepiness
during the day
• The pull of this drive builds up during wakefulness and
reaches its peak at sleep time
• Its strength declines during sleep with lowest point
upon awakening in the morning
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Adenosine and Homeostatic Sleep Drive
• A number of endogenous sleep producing substances
mediate the transition from prolonged wakefulness to
NREM sleep.
• Adenosine mediates this transition by inhibiting arousal-promoting
neurons of the basal forebrain.
• Caffeine is believed to promote wakefulness by blocking
adenosine receptors.
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Circadian Rhythm
• Virtually all living organisms exhibit metabolic,
physiologic, and behavioral circadian rhythms (about 24hour)
• Sleep / Wake Cycling (amount, time)
• Body temperature
• Hormone secretion - ACTH, LH, FSH, melatonin, TSH,
cortisol
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“The Master Biological Clock”
• endogenous Circadian Pacemaker regulates sleep-
wake and all other circadian rhythms
• resides in the suprachiasmatic nuclei (SCN) of the
hypothalamus.
• SCN are bilaterally paired nuclei located slightly above
the optic chiasm in the anterior hypothalamus.
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Circadian Clock Synchronizes with
Environment
• Circadian clocks are normally synchronized to
environmental cues by a process called entrainment.
• Light-dark cycle is the most potent entraining
stimulus.
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Circadian Output
• Information from the SCN is transmitted to the rest of the
body after input from the hypothalamus.
• Thus body organ response to the circadian rhythm is
controlled by the SCN and modulated by the
hypothalamus.
• (e.g. sleep-wake cycle, core body temperature, the release of
cortisol, thyroid stimulating hormone, melatonin etc.)
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Sleep Academic Award
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Sleep State Determination
• Electrographic
• Behavioral
• Neuronal activity
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Properties of Wake, REM, NREM
Behavioral
Wake
NREM
REM
Movement
frequent,
voluntary
infrequent,
episodic
inhibited
Thought
logical &
remembered
logical & not
remembered
illogical,
not
remembered
unless
awakened
Eyes
open,moving
closed, slow
or not moving
closed,
rapidly
moving
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Properties of Wake, REM, NREM
Electrographic
Wake
NREM
REM
desynch
synch
desynch
EOG
present
(eye movements)
slow or
absent
rapid
EMG
present
(muscle tone)
decreased
inhibited
EEG
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Clinical Evaluation of Sleep Problems
• Normal Variation
• Factors that impact on sleep
• Sleep Processes
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Factors that Impact on Sleep
Developmental
Circadian
Ultradian
Prior sleep deprivation
/ fragmentation
Neurologic
Cardiopulmonary
Gastrointestinal
Endocrine
Dermatologic
Upper respiratory
Allergy
Drugs
Psychiatric /
psychological
Infectious
Pain
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Sleep History and Sleep Log
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Sleep History
• Bedtime
• Excessive daytime sleepiness
• Awakenings
• Regularity
• Snoring
EXCESSIVE DAYTIME
SLEEPINESS
Scope of the Problem
• Sleepiness is problematic when it disrupts daily
living
• Problem sleepiness is estimated to affect 0.5 to
5% of the population
• But 20-25% of US population does shift work
• Problem sleepiness has two primary causes:
• Lifestyle factors
• Sleep disorders
Sleepiness vs. Fatigue
• Sleepiness reflects a biologic need; sleep is to sleepiness
as food is to hunger. Sleepiness refers specifically to an
increased likelihood of falling asleep. Fatigue refers to
many different conditions, some of which do not include
sleepiness. Fatigue refers specifically to increased
difficulty sustaining a high level of performance.
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Disorders of EDS
Insufficient sleep
Increased drive to sleep
Fragmented Sleep
•Inadequate sleep hygiene
•Insufficient Sleep syndrome
•Jet Lag/sleep deprivation
•Long sleeper
•Narcolepsy
•Idiopathic hypersomnia
•Circadian rhythm disorders
•Medical illness/Medications
•OSAS
•Central sleep Apnea
•RLS
•Parasomnias
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Consequences of EDS
• Loss of work efficiency
• Indirect health care costs
• Direct costs to business
• Motor vehicle accidents
• Depression/anxiety
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Sleep Disorders - Socioeconomic
Consequences
• More than 100,000 motor
vehicle accidents annually
are sleep-related.
• Disasters such as:
• Chernobyl,
• Three Mile Island,
• Challenger,
• Exxon Valdez
were officially attributed to
errors in judgement induced by
sleepiness or fatigue.
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Sleepy Driving is Fatal
• The increased fatality rate is likely due to a
combination of:
• Reduced Vigilance
• Slowed Reaction Times
• Loss of Steering Control
• Sleepiness represents a significant risk to driving
safety and may pose as great a risk as alcohol
• Motor vehicle accidents tend to peak during early
morning and mid-afternoon hours, in accordance with
times of increased sleep propensity
Assessing Sleepiness
• Patient history
• Observer history
• Scales, tests, subjective scores
• Objective measurement
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Evaluation of sleepiness
• Subjective measures/ objective measures
• May be discordant
• Under reported
• Physiologic testing may not be representative of actual conditions
that patients operate under
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Characteristic features of sleepiness
• Physiologic Sleepiness
• Biologic drive to sleep (measured by Sleep latency)
• Manifest sleepiness
• Change in individuals behavior from sleepiness
(performance, inability to stay awake, decreased
performance on vigilance testing)
• Introspective sleepiness
• Patients assessment of their sleep state
(questionnaires')
Physiologic sleepiness-MSLT
• Patients have four to five 20 minute opportunities to nap
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during the day
Unit of measure is minutes from lights out to sleep
onset
“Normal” is > 15 minutes
Pathologically sleepy is < 5 minutes
REM sleep during these naps is not expected
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Manifest sleepiness
• MWT
• 4-5 periods where patients are instructed to remain awake (after
overnight PSG)
• Document response to therapy
• Safe to perform their work after Tx
• Vigilance testing
• Driving simulators
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Introspective sleepiness
• Stanford sleepiness Scale
• Easy to use
• No reference values
• Not validated with physiologic sleepiness
• Epworth sleepiness Scale Score
• Widely used
• Mean SL on MSLT does not always correlate with score
• Can not replace physiologic testing
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Clues to Sleep Deprivation:
How much sleep is enough?
• “Normal” human range is 5-10 hours / night
• Alarm clock use indicates sleep curtailment
• Weekend catch-up indicates sleep curtailment
• Sleep loss proportional to number of jobs, kids
Sleep Hygiene
• Regular sleep-wake schedule
• Avoid caffeine
• Exercise
• Careful use of napping
• Avoid alcohol and nicotine
• Use bed only for sleep and sex
• Quiet, cool (65 degrees) sleeping room
Clues to SDB
Which snorers have apnea?
• Witnessed apneas
• “Heavy” snoring, impotence, sleepiness
• Hypertension
• Crowded upper airway
• Central obesity
• Neck circumference > 17/16
• BMI > 30
Clues to Narcolepsy:
When is sleepiness genetic?
• Symptom onset in adolescence
• 0.05 % population
• HLA linked-autoimmune
• Naps are refreshing
• Family history -25 % concordance in identical twins
• Deficiency of hypocretin/orexin
• The narcolepsy “tetrad”
The Narcolepsy Tetrad
• EDS
• Cataplexy
• Hypnagogic / hypnopopnic hallucinations
• Sleep paralysis
• (Disturbed nocturnal sleep)
Diagnosing Narcolepsy
• Compatible clinical history
• Rule out other causes (SDB, PLMS, sleep deprivation,
drugs)
• Overnight polysomnogram is normal and includes > 6
hours sleep
• Daytime MSLT shows sleepiness (mean sleep latency <
10 minutes) plus 2 or more SOREM’s
Restless Legs vs. Periodic Limb
Movements of Sleep
• RLS is a collection of
symptoms
• Diagnosis made by
history
• 80 % of those with
RLS have PLMS
• PLMS is an
electromygraphic
finding
• Diagnosis made in a
sleep lab
• 30% of those with
PLMS have RLS
Clues to a Movement Disorder:
Symptoms of RLS
• Unpleasant limb sensations
• Sensations precipitated by rest and relieved by activity
• Compelling motor restlessness
• Worsening of symptoms at night
Problem Sleepiness: History
• History of apneas, snoring
• Complaints of unpleasant limb sensations,
worse at night, relieved by activity, associated
with movement
• Medication history
• Sleep diary or habits
• Cataplexy, hallucinations, paralysis, family
history
• Severity of sleepiness: Epworth, car wrecks
Problem Sleepiness: Examination
• BMI, blood pressure, neck circumference, airway (SDB)
• Pupils (stimulant seeker)
• Neurologic and vascular exam (RLS)
• Thyroid (hypothyroidism)
Which Sleepy Patients Go To The
Sleep Lab?
• Those suspected of sleep apnea or narcolepsy
• Narcolepsy diagnosis requires PSG and MSLT; sleep
apnea diagnosis requires PSG
• RLS, sleep deprivation, medication effects usually
diagnosed clinically
Drug Effects
• Drugs can cause sleepiness 3 ways:
• Direct pharmacologic effect
• Disturbed sleep architecture
• Abrupt discontinuation (withdrawal)
• Two characteristics are particularly risky:
• Highly lipophilic
• Affecting cholinergic, dopaminergic, or histaminergic receptors
Clues to Drug-Induced Sleepiness:
Classes of Drugs
• Analgesics
• Antihypertensives
• Anti-asthmatic agents
• Antiparkinsonian
• Anticonvulsants
agents
• Antipsychotic agents
• Antidepressants
• Benzodiazepines
• Antihistamines
• Antiemetics
Sleep can be dangerous for
patients with lung diseases
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Thank You