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Chapter 21
Sleep and Sleep Disorders
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Functions of Sleep
• Period of inactivity and restoration of mental and physical
function
• Time for entering information acquired during periods of
wakefulness into memory
• Time for reestablishing communication between various
parts of the brain
• Time when other body systems restore their energy and
repair their tissues
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Anatomical Structures Involved in the
Sleep–Wake Cycle
• Thalamus
– All sensory information is relayed to the thalamus.
• Cerebral cortex
– All sensory information is relayed from the thalamus
to the cerebral cortex.
• Interneurons in the reticular formation of the
midbrain, pons, and brain stem
– They monitor and modulate the activity of various
circuits controlling wakefulness.
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Sleep–Wake Cycle
• Consists of a synchronous pattern of wakefulness and
sleep
• Wakefulness and sleep differ in terms of
– Awareness of environment
– Motor and eye movements
– Brain waves
• Sleep is characterized by alterations between non-REM
and REM sleep.
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Characteristics of REM and Non-REM Sleep
• REM Sleep
– Rapid eye movements
– Loss of muscle movements
– Vivid dreaming
– ANS changes
• Increases
– Blood pressure, heart rate, and respirations
• Decreases
– Cerebral blood flow and metabolic rate decrease
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Characteristics of REM and Non-REM Sleep
(cont.)
• Non-REM Sleep
– Quiet type of sleep
– Relatively inactive yet fully regulating brain
– Fully movable body
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Stages of Non-REM Sleep
• Stage 1
– Low-voltage, mixed-frequency EEG activity
– Occurs at sleep onset; brief (1 to 7 minutes)
transitional stage between wakefulness and true
sleep; person can be easily aroused.
– Transitional stage for repeated sleep cycles
throughout the night
• Stage 2
– Deeper sleep; lasts 10 to 25 minutes
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Stages of Non-REM Sleep (cont.)
– EEG activity interrupted by sleep spindles
• Stages 3 and 4
– Deep sleep; high-voltage, low-frequency (1 to 3 Hz)
waves; harder to arouse person
– Stage 3 (few minutes) transitional to stage 4 (20 to
40 minutes)
– Muscles of the body relax; posture adjusted
– Decreased blood pressure; slowed gastrointestinal
activity
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Breathing During Sleep
• Stages 1 and 2
– Cyclic waning and waxing of tidal volume and respiratory
rate
– May include brief periods of apnea (periodic breathing)
• Stages 3 and 4
– Breathing becomes more regular
• REM sleep
– Respiration become irregular, but not periodic, may
include short periods of apnea
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
• Normal sleeping patterns are marked by physiological
signs of relaxation and recuperation and marked
decreases in physical systems activities.
– True
– False
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Answer
• False
• Rationale: Sleeping involves cycling of many systems
from low levels to higher levels of activity.
Copyright © 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins
Regulation of the Sleep–Wake Cycle
• Circadian rhythm
– Sleep and wakefulness occur in a cyclical manner.
– Integrated into the 24-hour light–dark solar day
– Thought to be controlled by the suprachiasmatic
nucleus in the hypothalamus
• Melatonin
– Thought to help regulate the sleep–wake cycle
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International Classification of Sleep
Disorders
• Dyssomnias: disorders of initiating and maintaining
sleep and disorders of excessive sleepiness
• Parasomnias: undesirable phenomena that occur
primarily during sleep; do not disturb the sleep–wake
cycle
• Sleep disorders associated with other medical or
psychiatric disorders
• Proposed sleep disorders, such as pregnancy-induced
sleep disruptions
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Diagnostic Methods for Diagnosing Sleep
Disorders
• Sleep history
• Sleep log/diary
• Polysomnography
• Actigraphy
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Dyssomnias
• Circadian rhythm disorders
– Non–24-hour sleep–wake syndrome
– Acute shifts in the sleep–wake cycle
– Change in sleep phase disorders
– Advanced sleep phase syndrome
• Insomnia
– Acute or transient
– Chronic
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Treatment for Insomnia
• Education and counseling regarding better sleep habits
(sleep hygiene)
• Behavioral therapy aimed at changing maladaptive sleep
habits
• The judicious use of pharmacologic interventions
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Sleep Disorders
• Narcolepsy
– Disorder of daytime sleep attacks, cataplexy,
hallucinations at the onset of sleep and sleep
paralysis
• Motor disorders of sleep
– Periodic limb movement disorder
– Restless legs syndrome
– Obstructive sleep apnea
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Sleep Apnea
• Central sleep apnea
– Rare disorder involving the CNS
• Obstructive apnea
– Upper airway obstruction
• Apnea–hypopnea periods per hour
• Diagnosis
– Sleep studies
– EOG
– EEG
– Polysomnography
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Signs and Symptoms of Sleep Apnea
• Noisy snoring
• Insomnia
• Abnormal movements during sleep
• Morning headaches
• Excessive daytime sleepiness
• Cognitive and personality changes
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Signs and Symptoms of Sleep Apnea
(cont.)
• Sexual impotence
• Systemic hypertension
• Pulmonary hypertension, cor pulmonale
• Polycythemia
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Question
• Obesity most likely will be the cause of
______________.
− A. central apnea
− B. obstructive apnea
− C. teeth grinding
− D. sleep walking
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Answer
• B. obstructive apnea
• Rationale: Obstructive apnea is caused by upper
airway obstruction, which can result from morbid
obesity.
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Parasomnias
• Nightmares
• Sleep walking
• Sleep terrors
• Teeth grinding
• Bed wetting (enuresis)
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Sleep Cycles in Infants and Children
• Infants spend more time in REM sleep than adults.
– Inhibitory systems in the infant’s brain are relatively
immature.
• Children
– Irregular sleep habits, insufficient or too much sleep,
nightmares, sleep terrors, sleepwalking, and bedwetting
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Causes of Sleep Disorders in the Elderly
• Age-related changes in sleep architecture
• Secondary sleep disturbances
• Primary sleep disorders
• Lack of exercise
• Poor sleep habits
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Factors Predisposing Elderly to Sleep
Disturbances
• Physical and mental illness
– Arthritic pain, respiratory problems, cardiac disease,
neurologic disorders
• Medication effects
• Emotional stress
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