Claim: Sleep is undisturbed by any forces.
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.
As it disrupts normal sleep , those affected may experience sleepiness or feel tired during the day.