A sleep study (polysomnography) records brain waves, eye and muscle activity, heart rhythm, breathing, airflow, oxygen levels and limb movements overnight to monitor sleep stages and detect disorders like sleep apnea, restless legs or narcolepsy. Sensors attach to scalp, face, chest and limbs; video and audio may be used. Technicians monitor and later score the data; some tests can be done at home with simplified equipment.

If you can’t fall asleep during an in‑lab sleep study, technicians will try calming measures (darkening the room, relaxation, position changes) and may extend monitoring. Some centers may rarely give a short‑acting sedative; if sleep still doesn’t occur, the study can be rescheduled or replaced with home testing. Some measurements (oxygen, breathing, EEG while awake) remain useful, but sleep‑dependent tests (e.g., MSLT) may be invalid.

Before the sleep study: avoid caffeine, alcohol, and naps the day of the test; follow any medication instructions; shower and avoid hair products and lotions. Bring a list of medications, a sleep diary, comfy sleepwear, pillow, and toiletries. Arrive on time. Technicians will attach sensors and guide lights‑out time; expect overnight monitoring and follow-up to review results. Ask staff any questions.

Most sleep apnea cases are obstructive: repeated collapse or blockage of the upper airway during sleep. This happens when throat muscles relax, letting soft tissues fall back and narrow the airway. Risk factors include excess weight, enlarged tonsils, a large neck, narrowed airway anatomy, alcohol or sedative use, and nasal congestion. Central sleep apnea, less common, results from impaired brain signaling to breathe.

Costs vary by test type and country. In the U.S., an in‑lab polysomnography typically ranges from about $700–$3,000 (before insurance); home sleep apnea tests commonly cost $100–$500. In the U.K., studies are usually free through the public health system but private testing is roughly £400–£1,200. In India, overnight sleep studies generally run about ₹2,500–₹25,000. Insurance often covers part or all of the expense.

A standard in‑lab overnight sleep study (polysomnography) typically records one full night — about 6–8 hours. Split‑night studies (diagnostic then CPAP titration) can occupy the whole night. Home sleep‑apnea tests usually record roughly 6–8 hours, depending on your sleep. Daytime tests (e.g., multiple sleep latency testing) take most of a day, often about 8–10 hours with multiple nap opportunities.