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Overview of Sleep Ritu G. Grewal, MD. Key to Evaluation of Sleep Problems . Sleep Physiology Factors that impact on sleep Sleep History Polysomnogram. Defining Sleep.

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Overview of sleep ritu g grewal md

Overview of SleepRitu G. Grewal, MD

Key to evaluation of sleep problems
Key to Evaluation of Sleep Problems

  • Sleep Physiology

  • Factors that impact on sleep

  • Sleep History

  • Polysomnogram

Defining sleep
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


Differentiating sleepiness from tiredness or fatigue
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.

Responsiveness to stimuli is not completely absent in sleep
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.


  • Active

  • Complex

  • Highly Regulated

  • Involves different neuronal groups

  • Purpose is not understood

  • Essential

  • Composed of two fundamentally different states : REM sleep & NREM sleep

Sleep consists of two strikingly different states
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

How much sleep does one need
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

Three states of being
Three States of Being

  • Wake

  • REM Sleep

  • Non-REM Sleep

Two drives regulating sleep
Two Drives Regulating Sleep sleep rhythms

  • 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

Homeostatic factor
Homeostatic Factor sleep rhythms

  • 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.

Homeostatic regulation of sleep
Homeostatic Regulation of Sleep sleep rhythms

  • 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

Adenosine and homeostatic sleep drive
Adenosine and Homeostatic Sleep Drive sleep rhythms

  • 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.

Circadian rhythm
Circadian Rhythm sleep rhythms

  • Virtually all living organisms exhibit metabolic, physiologic, and behavioral circadian rhythms (about 24-hour)

  • Sleep / Wake Cycling (amount, time)

  • Body temperature

  • Hormone secretion - ACTH, LH, FSH, melatonin, TSH, cortisol

The master biological clock
“The Master Biological Clock” sleep rhythms

  • 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.

Circadian clock synchronizes with environment
Circadian Clock Synchronizes with Environment sleep rhythms

  • Circadian clocks are normally synchronized to environmental cues by a process called entrainment.

  • Light-dark cycle is the most potent entraining stimulus.

Circadian output
Circadian Output sleep rhythms

  • 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.)

Sleep Academic Award sleep rhythms22

Sleep state determination
Sleep State Determination sleep rhythms

  • Electrographic

  • Behavioral

  • Neuronal activity

Properties of wake rem nrem behavioral
Properties of Wake, REM, NREM Behavioral sleep rhythms


Movement frequent, infrequent, inhibited

voluntary episodic

Thought logical & logical & not illogical,

remembered remembered not remembered

unless awakened

Eyes open,moving closed, slow closed,

or not moving rapidly


Properties of wake rem nrem electrographic
Properties of Wake, REM, NREM sleep rhythms Electrographic


EEG desynch synch desynch

EOG present slow or rapid

(eye movements) absent

EMG present decreased inhibited

(muscle tone)

Clinical evaluation of sleep problems
Clinical Evaluation of Sleep Problems sleep rhythms

  • Normal Variation

  • Factors that impact on sleep

  • Sleep Processes

Factors that impact on sleep
Factors that Impact on Sleep sleep rhythms




Prior sleep deprivation / fragmentation






Upper respiratory



Psychiatric /




Sleep history
Sleep History sleep rhythms

  • Bedtime

  • Excessive daytime sleepiness

  • Awakenings

  • Regularity

  • Snoring

Scope of the problem
Scope of the Problem sleep rhythms

  • 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 vs. Fatigue sleep rhythms

  • 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.

Consequences of eds
Consequences of EDS sleep rhythms

  • Loss of work efficiency

    • Indirect health care costs

    • Direct costs to business

  • Motor vehicle accidents

  • Depression/anxiety

Sleep disorders socioeconomic consequences
Sleep Disorders - Socioeconomic Consequences sleep rhythms

  • 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.

Sleepy driving is fatal
Sleepy Driving is Fatal sleep rhythms

  • 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
Assessing Sleepiness sleep rhythms

  • Patient history

  • Observer history

  • Scales, tests, subjective scores

  • Objective measurement

Evaluation of sleepiness
Evaluation of sleepiness sleep rhythms

  • Subjective measures/ objective measures

    • May be discordant

    • Under reported

    • Physiologic testing may not be representative of actual conditions that patients operate under

Characteristic features of sleepiness
Characteristic features of sleepiness sleep rhythms

  • 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
Physiologic sleepiness-MSLT sleep rhythms

  • Patients have four to five 20 minute opportunities to nap 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

Manifest sleepiness
Manifest sleepiness sleep rhythms

  • 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

Introspective sleepiness
Introspective sleepiness sleep rhythms

  • 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

Clues to sleep deprivation how much sleep is enough
Clues to Sleep Deprivation: sleep rhythmsHow 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
Sleep Hygiene sleep rhythms

  • 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
Clues to SDB sleep rhythmsWhich 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
Clues to Narcolepsy: sleep rhythmsWhen 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
The Narcolepsy Tetrad sleep rhythms

  • EDS

  • Cataplexy

  • Hypnagogic / hypnopopnic hallucinations

  • Sleep paralysis

  • (Disturbed nocturnal sleep)

Diagnosing narcolepsy
Diagnosing Narcolepsy sleep rhythms

  • 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
Restless Legs vs. Periodic Limb Movements of Sleep sleep rhythms

  • 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
Clues to a Movement Disorder: sleep rhythmsSymptoms of RLS

  • Unpleasant limb sensations

  • Sensations precipitated by rest and relieved by activity

  • Compelling motor restlessness

  • Worsening of symptoms at night

Problem sleepiness history
Problem Sleepiness: History sleep rhythms

  • 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
Problem Sleepiness: Examination sleep rhythms

  • 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
Which Sleepy Patients Go To The Sleep Lab? sleep rhythms

  • 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
Drug Effects sleep rhythms

  • 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
Clues to Drug-Induced Sleepiness: Classes of Drugs sleep rhythms

  • Analgesics

  • Anti-asthmatic agents

  • Anticonvulsants

  • Antidepressants

  • Antihistamines

  • Antihypertensives

  • Antiparkinsonian agents

  • Antipsychotic agents

  • Benzodiazepines

  • Antiemetics

Thank you
Thank You sleep rhythms