AP® Psychology · Unit 1 · Topic 1.5
Sleep Disorders
Sleep disorders are specific breakdowns in the normal sleep cycle: apnea fragments sleep with breathing pauses, insomnia blocks sleep onset or continuity, narcolepsy intrudes REM into waking life, and REM behavior disorder lets the body move during dreams.
Each sleep disorder breaks a different piece of the normal sleep machine. Sleep apnea is a breathing problem: the airway collapses or the brain fails to signal breathing muscles, so the sleeper stops breathing, oxygen drops, and the brain triggers a micro-arousal just long enough to gasp and restart. This can happen dozens of times a night, visible on a sleep chart as a jagged, fragmented record, yet the arousals are so brief and shallow that no lasting memory forms. The person wakes up exhausted with no idea why.
Insomnia is trouble falling asleep or staying asleep, or waking too early, with daytime fatigue as a result. Narcolepsy is a disorder of REM intrusion: the brain cannot properly regulate the boundary between sleep and waking, so REM sleep, and its paralysis of voluntary muscles, bursts into the middle of the day, causing sudden sleep attacks and sometimes cataplexy, a sudden loss of muscle tone. REM sleep behavior disorder is almost the opposite problem: the muscle paralysis that normally locks the body still during REM fails, so the sleeper physically acts out whatever is happening in the dream. Sleepwalking is different from all of these. It happens during deep non-REM sleep, when dreaming is minimal, so a sleepwalker is not performing a dream's storyline; the body is active while the dreaming mind is largely offline.
Treating apnea, often with a continuous airway pressure device, removes the breathing pauses and the fragmentation disappears from the sleep chart, restoring longer uninterrupted stretches of deep and REM sleep. That matters beyond the bedroom: chronic sleep loss from any of these disorders raises stress hormones and weakens immune defenses, linking a fragmented night directly to the body's long-term health.
Key terms
- Sleep apnea
- A disorder of repeated breathing pauses during sleep that cause brief, often unremembered arousals.
- Insomnia
- Persistent difficulty falling asleep, staying asleep, or waking too early, causing daytime impairment.
- Narcolepsy
- A disorder where REM sleep intrudes into waking life, causing sudden sleep attacks and sometimes muscle collapse.
- REM sleep behavior disorder
- A condition where the muscle paralysis of REM sleep fails, letting the sleeper physically act out dreams.
- Micro-arousal
- A very brief, shallow waking response, often too short to be consciously remembered.
Watch it explained
- How it worksHow does sleep apnea shatter a night into fragments on a sleep chart?
- How it worksWalk me through what goes wrong in insomnia, narcolepsy, and REM sleep behavior disorder.
- Common mistakeWhy isn't sleepwalking a person acting out the dream they are having?
- Going furtherWhat changes on the sleep chart once apnea is treated?
- Ties togetherHow does chronic sleep loss connect to the stress and immune findings in health psychology?
Check yourself
End of topic.