Sleep and Sleep Disorders

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


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
These monitor and modulate the activity of various circuits controlling wakefulness
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
Characteristics of REM and Non-REM Sleep
REM Sleep
Rapid eye movements
Loss of muscle movements
Vivid dreaming
Non-REM Sleep
Quiet type of sleep
Relatively inactive yet fully regulating brain
Fully movable body
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
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 – 40 min.)
Muscles of the body relax; posture adjusted
Decreased blood pressure; slowed gastrointestinal activity
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 included short periods of apnea
Regulation of the Sleep-Wake Cycle
Circadian rhythm
Sleep and wakefulness occur in a cyclical manner
Integrated into the 24-hr light-dark solar day
Thought to be controlled by SCN in the hypothalamus
Melatonin
Thought to help regulate the sleep-wake cycle
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
Diagnostic Methods for Diagnosing Sleep Disorders
Sleep history
Sleep log/diary
Polysomnography

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
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
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
Signs and Symptoms of Sleep Apnea
Noisy snoring
Insomnia
Abnormal movements during sleep
Morning headaches
Excessive daytime sleepiness
Cognitive and personality changes
Signs and Symptoms of Sleep Apnea (cont.)
Sexual impotence
Systemic hypertension
Pulmonary hypertension cor pulmonale
Polycythemia

Parasomnias
Nightmares
Sleep walking
Sleep terrors
Teeth grinding
Bed wetting (enuresis)
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
Factors Predisposing Elderly to Sleep Disturbances
Physical and mental illness
arthritic pain, respiratory problems, cardiac disease, neurologic disorders
Medication effects
Emotional stress