IzBen C. Williams, MD, MPH Instructor. Lecture 9 NORMAL SLEEP AND SLEEP-WAKE DISORDERS

BEHAVIORAL SCIENCE

IzBen C. Williams, MD, MPHInstructor

Lecture 9

NORMAL SLEEP AND

SLEEP-WAKE DISORDERS

DRIVESSleep should be considered in the context of

biological “drives” DRIVES are innate biological forces, which

are manifested in all forms of animal life. Some others areHunger, thirst, pain, temperature, sex,

Sleep has many of the attributes of a driveThe only way to overcome that drive is to

sleep

DRIVESSleep deprivation leads to increased urge to

sleep and to extended periods of sleep immediately following the deprivation

After several days of sleep deprivation, a confusional state may occur withDisordered attention, emotional labilityReduced memory, DelusionsHallucinations (occasionally)

DRIVESThe physiologic function of sleep is unclearOur current understanding suggests that

people follow the urge to sleep in order to avoid the consequences of sleep deprivation

Freud’s explanation was that sleep provided a time for dreaming and discharging unconscious wishes, and for expressing unconscious fantasies which are unacceptable to conscious thought and expression

Sleep PhysiologyMost animals experience a daily cycle of

changes in levels of arousal as well as sleep and waking

Normal sleep is an active process that requires activity of neurons in the brainstem

Neurophysiologic studies demonstrate that nerve cells in the pontine reticular formation begin to discharge minutes prior to the onset of certain stages of sleep

Sleep PhysiologyOur awake state is characterized by two

associated EEG patternsAlpha waves: over the occipital and parietal

lobes are seen when a person relaxes with eyes closed

Beta waves: over the frontal lobes are seen with active concentration

Sleep latency (time between going to bed and falling asleep) is usually less than 20 minutes

Normal Sleep Physiology

During sleep, we usually pass through five Stages Stages 1, 2, 3, and 4 also called non-rapid eye

movement sleep) or slow wave sleep, and Stage 5 - Rapid Eye Movement (REM) sleep

These phases progress in a cycle from the waking state, then the cycle restartsThe time required to pass through the complete

sequence of sleep stages is about 90 minutes, and the cycle is repeated some three to five times each night

Normal EEG

Normal Sleep Architecture

Sleep architecture: The characteristic map of EEG tracings reflecting the various stages of sleep

Sleep architecture: Changes with age….the elderly have:

reduced REM sleep reduced delta sleep (stage 3-4, or slow wave)reduced total sleep timeIncreased night-time wakenings

Sleep Architecture


Sleep architecture: Sedative agents (eg. alcohol, barbiturates

and benzodiazepines) are also associated with reduced REM sleep and delta sleep

Most delta sleep occurs during first half of sleep cycle

The longest REM periods occur during the second half of the sleep cycle


During REM sleep high levels of brain activity occur: Average time between first REM period and falling

asleep (Rem latency) is 90 minutesREM periods lasting aprox. 10-40 minutes each

occur about every 90 minutes throughout the nightREM rebound: making up for lost REM sleep with

subsequent increased REM sleepExtended REM deprivation or total sleep

deprivation may result in transient psychiatric symptomatology, usually anxiety or psychosis

Hypnogram

Neurotransmitters and Sleep

Neurotransmitters control many aspects of sleep.Falling asleepStaying asleepGetting deep sleep (REM)The waking process


Neurotransmitters may play either an excitatory role or an inhibitory role in sleep:Excitatory: energizing, motivating, provide

focus, revving up the systemInhibitory: calming, relaxing, sleep inducing,

slowing down the system


Elevated levels of excitatory neurotransmitters can lead to decrease in total sleep time and REM sleep Excitatory neurotransmitters related to

sleep: Epinephrine (adrenalin)Norepinephrine (noradrenalin)Phenylethylamine (PEA)GlutamateHistamine


Acetyl Choline:Increased levels of Acetyl Choline in the

reticular formation, both increase sleep time and REM sleep.

Acetyl choline levels, total sleep time, and REM sleep decrease in normal aging as well as in Alzheimer’s disease


Increased levels of inhibitory neurotransmitters can increase both sleep time and delta sleep. Inhibitory neurotransmitters related to sleep:Serotonin, GABA, Taurine, GlycineDamage to the dorsal raphe nuclei, which

produce serotonin, decrease both these measuresTreatment with antidepressants, which increase

serotonin availability, can improve sleep in depressed patients


Dopamine:Increased levels of Dopamine decrease

total sleep time.Treatment with antipsychotics, which block

dopamine receptors, may improve sleep in patients with psychotic symptoms


During the day, excitatory neurotransmitter levels are high, providing the energy and motivation necessary to carry out normal functions.

During the evening, excitatory levels drop and inhibitory transmitter levels rise, preparing the body for rest.


Around bed time, the drop in excitatory neurotransmitter levels and rise in inhibitory levels signal the production of melatonin.

During the night, low levels of excitatory transmitters and increased levels of inhibitory transmitters and melatonin are what the body needs for deep, restful sleep.

Hormones and sleep

Melatonin: Known as the “sleep hormone”, and is

responsible for inducing sleep in humans.

Melatonin is made from serotonin in the body. Low levels of serotonin could lead to low levels of melatonin.

Hormones and sleep

Cortisol, the “stress hormone” is produced by the adrenal gland.

People experiencing high amounts of stress may have elevated cortisol levels. High night time cortisol levels can cause sleep disturbances.

Sleep-Wake Disorders

Classification of Sleep DisordersA. Dyssomnias: Characterized by problems in the

timing, quality or amount of sleep. They include:InsomniaHypersomnia

Narcolepsy, Kleine-Levin Syndrome (primary hypersomnias)Sleep Apnea (breathing related sleep disorder)

as well as: Circadian rhythm sleep disorder, Nocturnal myoclonus (restless leg syndrome)


Classification of Sleep DisordersB. Parasomnias: characterized by

abnormalities in physiology or in the behavior associated with sleep. They include:BruxismSleepwalkingSleep terrorREM sleep behaviorNightmare disorders


Insomnia: Difficulty falling asleep or staying asleep that occurs……..Three times a week for at least one monthLeads to sleepiness during the day, orCauses problems fulfilling social or

occupational obligations.It is present in at least 30% of the population


Factors contributing to Insomnia:Situational problems Medical disordersAgingDrug-related episodesPsychological conditions (affective, anxiety,

psychotic)


Hypersomnia1) Narcolepsy: (usually occurs before age 40, and

includes one or more of the following conditions)i. Sleep attacks: sudden, reversible, short, occurs

during any type of activity; direct progression to REM sleep; awakes refreshed; refractory period of 1-5 hrs before another attack

ii. Cataplexy: sudden loss of muscle tone; small group to general; slumping to ground; often initiated by emotional outburst; lasts seconds to 30 minutes


Hypersomnia1) Narcolepsy: (cont’d)

iii. Sleep paralysis: flaccid muscle tone with full consciousness, either during awakening or while falling asleep; there’s usually intense fear, occasionally followed by auditory hallucinations

iv. Hallucinations (hypnagogic or hypnopompic)The occurrence of symptoms of the narcoleptic

triad are: 1) sleep attacks almost 100%; sleep attacks and cataplexy ~70%; sleep paralysis alone ~5%


Hypersomnia2) Kleine-Levin syndrome: Hypersomnic

attacks may last up to 20 hrs, 3-4 times a year, followed by confusion upon awakening. This syndrome is a separate entity from narcolepsy


Hypersomnia3) Sleep apnea: Apneic episodes occur in

both REM and NREM sleep; noisy, stertorous snoring and hypersomnolence the next day, are common;

i. Central apnea: cessation of respiratory movement with loss of air flow

ii. Obstructive apnea: persistent respiratory effort but upper airway blockage


Stage 4 Sleep DisordersEnuresis: seen with variable nightly

occurrence in children; usually stage fourSomnambulism: mostly in children,

usually in stage 3 and 4 (amnesia for episode)

Pavor nocturnus: (night terrors) usually in children, predominantly in stage 4 (amnesia for episode)

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IzBen C. Williams, MD, MPH Instructor. Lecture 9 NORMAL SLEEP AND SLEEP-WAKE DISORDERS