Insomnia is persistent difficulty falling asleep, staying asleep, or getting restful sleep, leading to daytime fatigue.
Narcolepsy causes excessive daytime sleepiness and sudden sleep episodes, while in sleep apnea breathing repeatedly stops and starts during sleep, often causing awakenings the person doesn't notice.
Somnambulism (sleepwalking) typically occurs during deep NREM sleep.
In REM sleep behavior disorder, the normal REM paralysis is missing, so people physically act out their dreams.
Disrupted sleep affects how we think, feel, and function while awake; treatment and regular sleep schedules can improve well-being.
Key terms
insomnia
Persistent difficulty falling asleep, staying asleep, or getting restful sleep (SOMN = sleep, so "without sleep").
narcolepsy
Excessive daytime sleepiness and sudden episodes of sleep (related to narcotics – looks suddenly drugged).
sleep apnea
Breathing repeatedly stops and starts during sleep, briefly waking the person again and again.
somnambulism
Sleepwalking: walking or doing other activities while asleep (SOMN = sleep, AMBUL = walk).
REM sleep behavior disorder
The normal paralysis of REM is missing, so a person acts out dream movements while asleep.
Watch out
Sleepwalking happens in deep NREM sleep, while acting out dreams happens in REM sleep behavior disorder.
Sleep apnea can leave someone tired despite a full night in bed, often without them realizing they kept waking.