[ Psychiatric ] Sleep Disorders 1

Normal Sleep-Wake Cycle: Duration of NREM to REM cycles

NREM → REM cycles repeat every ~90 minutes.

NREM sleep (Stages 1-3): General function

Responsible for the transition from wakefulness to deep restorative sleep.

NREM Stage 1 sleep: EEG findings

Theta waves on EEG.

NREM Stage 1 sleep: Physiological phase

Transition phase (wake → sleep).

NREM Stage 2 sleep: EEG findings

Sleep spindles + K complexes.

NREM Stage 2 sleep: Environmental awareness

Decreased awareness of environment.

NREM Stage 2 sleep: Associated clinical behavior

Bruxism may occur.

NREM Stage 3 sleep: EEG findings and depth

Delta waves (deepest sleep).

NREM Stage 3 sleep: Arousability

Highest arousal threshold.

NREM Stage 3 sleep: Physiological significance

Most restorative sleep phase.

REM sleep: Timing of initial onset

Occurs about 90 minutes after sleep onset.

REM sleep: Temporal distribution

More frequent in the early morning hours.

REM sleep: EEG characteristic

EEG resembles wakefulness.

REM sleep features: Cognitive experience

Vivid dreaming.

REM sleep features: Motor characteristic

Muscle atonia (paralysis of skeletal muscles).

REM sleep features: Genitourinary characteristic

Penile erection (normal physiological finding).

REM sleep features: Specific EEG waveform

Sawtooth waves on EEG.

REM sleep neurochemistry: Elevated neurotransmitter

↑ acetylcholine (ACh).

REM sleep neurochemistry: Decreased neurotransmitters

↓ serotonin & norepinephrine activity.

Age-related sleep changes: Increased characteristics

↑: night awakenings, sleep fragmentation/lighter sleep.

Age-related sleep changes: Decreased characteristics

↓: total sleep efficiency, slow-wave (deep) sleep, REM sleep.

Sleep disorders: Dyssomnias definition

Insufficient, excessive, or altered timing of sleep.

Sleep disorders: Parasomnias definition

Unusual sleep-related behaviors.

Insomnia: Epidemiology

MC sleep disorder.

Insomnia: Functional consequence

Results in nonrestorative sleep or impaired daytime functioning.

Insomnia clinical features: Initiation issue

Difficulty falling asleep (sleep-onset insomnia).

Insomnia clinical features: Maintenance issue

Difficulty staying asleep (sleep-maintenance insomnia).

Insomnia clinical features: Terminal issue

Early morning awakening with inability to return to sleep.

Insomnia clinical features: Quality issue

Nonrestorative sleep (waking unrefreshed)