Polysomnography (PSG): the sleep study, explained
Last updated: 2026-10-28
Quick answer
Polysomnography (PSG) is the clinical name for a sleep study — a test that records your breathing, oxygen, heart rate, snoring and body position while you sleep to diagnose conditions like obstructive sleep apnea. A full Level 1 polysomnography is done overnight in a hospital lab; a Level 3 home study measures the core breathing and oxygen channels in your own bed. For most people with snoring and daytime sleepiness, the home version gives the answer a doctor needs at a fraction of the cost.
What polysomnography measures
Polysomnography records several signals through the night at once. A full study tracks brain waves, eye movements, airflow, breathing effort, blood oxygen (SpO2), heart rate, snoring and body position. From these a specialist scores your AHI (breathing pauses per hour), ODI (oxygen dips) and sleep stages.
Those numbers are what confirm — or rule out — obstructive sleep apnea and grade how severe it is.
Why it is called polysomnography
The word is literal: poly for many, somnus for sleep, graphy for recording. Many recordings of sleep at once. That is the whole idea — no single signal identifies sleep apnea, so the test watches several at the same time and looks at how they move together.
A breathing pause only counts as an apnea if the airflow channel shows the airflow stopping, and it is graded by what happens next: whether the oxygen drops, whether the effort belts show you still straining to breathe, and whether you surface out of sleep. A machine that measured only one of those would miss most of the picture, which is why a pulse oximeter on its own is not a sleep study.
In-lab (Level 1) vs at-home (Level 3)
A Level 1 attended polysomnography is the full test, done overnight in a hospital sleep lab with a technologist watching. It is the most detailed, and the most expensive and inconvenient — a private lab PSG in Kerala typically costs ₹8,000–₹15,000.
A Level 3 home study — 'polysomnography at home' — records the core breathing and oxygen channels with a small device you wear in your own bed. It is clinically validated for diagnosing obstructive sleep apnea in people with typical symptoms, and avoids a night in hospital. Complex cases may still need a full lab study, which your doctor can advise.
Getting a polysomnography in Kerala
Current prices for every option are on our polysomnography test in Kerala page, and the wider comparison is in sleep study cost in Kerala. The short version: a SleepEase Level 3 home study is ₹2,500 all-in, against ₹8,000–₹15,000 for a private lab PSG.
You do not need a referral to book a home study. If you already have a prescription for polysomnography from a doctor, share it and we will note it on your report. Message SleepEase on WhatsApp and a technician comes to your home across Kerala.
Related: sleep study pricing · cost in Kerala · CPAP & BiPAP rental · buy a CPAP machine · home test in Kozhikode · book a test
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- Can I do a sleep study if I only sleep 5 hours?
- CPAP vs BiPAP: the difference and which you need
- Normal sleep study numbers: AHI, ODI, SpO2 and the rest of the report
- Obstructive vs central sleep apnea: what's the difference?
- What is a home sleep apnea test (HSAT)?