Claim: Sleep can be disrupted by medical conditions.
Evidence: Humans may suffer from various sleep disorders , including dyssomnias , such as insomnia , hypersomnia , narcolepsy , and sleep apnea ; parasomnias , such as sleepwalking and REM behavior disorder ; bruxism ; and circadian rhythm sleep disorders.
Narcolepsy is a long-term neurological disorder that involves a decreased ability to regulate sleep-wake cycles.