This document defines sleep and outlines the physiology and stages of sleep. It discusses factors that influence sleep such as circadian rhythms, neurotransmitters, and sleep cycles. Common sleep disorders like insomnia, narcolepsy, sleep apnea, and parasomnias are explained. Treatment options include behavioral therapies, medications, surgery, and lifestyle changes. Hospitalization can cause sleep disturbances, and medical conditions and drugs may also disrupt sleep. Nursing assessments and interventions aim to promote restful sleep.