Sleep medicine
Sleep medicine is the clinical field focused on sleep, wakefulness, circadian timing, and sleep disorders, including diagnosis, testing, behavior change, devices, medicines, and long-term care.
What sleep medicine is
Sleep medicine is a clinical field focused on sleep, wakefulness, circadian rhythms, and disorders that disturb rest or daytime function. It overlaps with neurology, pulmonology, psychiatry, psychology, cardiology, endocrinology, pediatrics, geriatrics, dentistry, and public health. The goal is to understand why sleep is not restorative, why someone is too sleepy, or why breathing, movement, behavior, or timing changes during sleep.
Sleep and circadian timing
Sleep is not simply the absence of activity. The brain cycles through non-REM and REM sleep, while breathing, heart rate, hormones, temperature, memory processing, and immune function change through the night. Circadian rhythms help time sleep and wakefulness across the 24-hour day. Light exposure, work schedules, travel, age, medicines, illness, and habits can all shift that timing.
Common sleep disorders
Sleep medicine covers insomnia, sleep-related breathing disorders such as obstructive sleep apnea, central disorders of hypersomnolence such as narcolepsy, circadian rhythm sleep-wake disorders, restless legs syndrome, periodic limb movements, REM sleep behavior disorder, sleepwalking, night terrors, nightmares, and other parasomnias. Some conditions are uncomfortable; others can affect safety, mood, cardiovascular risk, school, work, or driving.
Evaluation
A sleep evaluation starts with the story: bedtime, wake time, naps, snoring, witnessed pauses in breathing, sleepiness, shift work, caffeine, alcohol, medicines, pain, mood, neurologic symptoms, and bed partner observations. Sleep diaries and questionnaires can reveal patterns. The same complaint, such as fatigue, may come from insomnia, sleep apnea, depression, anemia, medication effects, circadian misalignment, or several factors at once.
Sleep studies
Testing is chosen for the question being asked. Polysomnography records signals such as brain waves, eye movement, muscle activity, breathing, oxygen level, heart rhythm, body position, and limb movement during sleep. Home sleep apnea testing can be useful for selected patients with suspected obstructive sleep apnea. Actigraphy can estimate sleep-wake patterns over days or weeks. Not every sleep problem needs a lab test.
Treatment options
Treatment may include sleep schedule changes, cognitive behavioral therapy for insomnia, light timing, treatment of breathing disorders with CPAP or other devices, oral appliances, weight or alcohol-related counseling, management of nasal obstruction, medication review, medicines for selected disorders, treatment of restless legs triggers, safety planning for parasomnias, or referral to another specialty. Durable improvement often depends on matching treatment to the actual mechanism.
Sleep in daily life
Sleep medicine is also practical medicine. Bedroom routines, screen timing, irregular schedules, caregiving, pain, anxiety, school start times, overnight work, travel, and untreated medical problems can all shape sleep. Healthy sleep habits can help, but advice such as 'just go to bed earlier' is often too simple when biology, work, illness, or caregiving push against a person's schedule.
Why it matters
Sleep affects attention, memory, mood, metabolism, immune response, blood pressure, heart rhythm, pain sensitivity, reaction time, and quality of life. Sleep disorders are often treatable, but they can be missed because symptoms appear as fatigue, irritability, poor concentration, morning headaches, depression, or accidents. Sleep medicine matters because better sleep can change both night and day.