At a glance
Polysomnography is an overnight diagnostic test that records what your body does while you sleep, giving doctors a detailed picture of your sleep quality and any breathing or movement problems that occur.
During the test, sensors attached to your scalp, face, chest, and legs pick up brain waves (the electrical signals your brain produces), eye movements, muscle activity, heart rhythm, airflow through your nose and mouth, blood oxygen levels, and chest movement. All of these signals are recorded at the same time, so the sleep specialist can see exactly which stage of sleep you were in when any problem occurred and how often it happened through the night.
Medical Condition
Doctors order polysomnography when a patient's symptoms suggest a sleep disorder that cannot be diagnosed by a simple questionnaire or a daytime clinic visit.
- Obstructive sleep apnoea (OSA): repeated pauses in breathing caused by the throat relaxing and blocking the airway during sleep.
- Central sleep apnoea: breathing pauses caused by the brain failing to send the correct signals to the breathing muscles.
- Narcolepsy: sudden, uncontrollable episodes of falling asleep during the day.
- REM sleep behaviour disorder: acting out vivid dreams, sometimes violently, while still asleep.
- Periodic limb movement disorder: repeated involuntary leg kicks or arm jerks during sleep.
- Restless legs syndrome that has not improved with standard treatment.
- Unexplained excessive daytime sleepiness that has not responded to initial evaluation.
- Parasomnias (abnormal behaviours during sleep) such as sleepwalking or night terrors in adults.
- Monitoring the effect of treatment, such as checking whether a CPAP (continuous positive airway pressure) device is working correctly.
Polysomnography is generally not the first step for everyone who sleeps poorly. Patients whose main complaint is simple difficulty falling asleep or staying asleep (insomnia without daytime sleepiness) are usually assessed in other ways first, because the test is unlikely to change their management. Children with suspected sleep disorders may need a paediatric sleep laboratory rather than an adult facility.
Risks & Complications
Polysomnography is a non-invasive recording test with no needles, no radiation, and no sedation, so its risk profile is very low.
- Skin irritation or mild redness where the electrode paste or adhesive was applied, which usually settles within a day.
- Difficulty sleeping in an unfamiliar environment, which can occasionally affect the quality of the recording.
- Mild scalp tenderness from the electrodes, resolving quickly after removal.
- Rarely, a slight allergic skin reaction to the electrode gel or adhesive tape.
Preparation & Procedure
On the day of the study, you wash your hair and avoid applying conditioner, oils, hairspray, or styling products, because residue on the scalp interferes with how the electrodes pick up brain signals. Avoid caffeine (coffee, tea, energy drinks, cola) from the afternoon onward, and skip alcohol that day, as both alter sleep patterns and can make the results harder to interpret.
Your sleep clinic will give you specific instructions about your regular medications. In most cases you continue taking them as usual, but some medications that affect the nervous system may need to be paused at your doctor's direction. Bring a list of everything you take.
Arrive at the sleep laboratory at the time you are given, usually in the early evening. Bring comfortable sleepwear, your usual pillow if you prefer, and anything you normally need for your bedtime routine. You do not need to fast before a standard polysomnography.
Here is what typically happens once you arrive:
- A sleep technologist meets you and explains what will happen during the night.
- You change into your sleepwear and settle into the private room prepared for you.
- The technologist applies electrodes to your scalp using a water-based paste, and attaches sensors near your eyes and chin.
- Belts are placed around your chest and abdomen to measure breathing effort.
- A small clip is placed on your finger to measure blood oxygen levels (a pulse oximeter).
- A thin sensor is positioned near your nose and mouth to detect airflow.
- Electrodes are attached to your legs to detect limb movements.
- All leads are connected to a recording box that you can carry if you need to use the bathroom.
- The lights are turned off at roughly your normal bedtime, and recording begins.
- A technologist monitors the signals from an adjoining room throughout the night and can speak with you through an intercom if needed.
- You are woken in the morning, the sensors are removed, and you are free to leave, usually in time for a normal morning.
Aftercare
Most people leave the sleep laboratory in the morning and return to their normal daily activities straight away, including driving, unless their doctor has advised otherwise because of a suspected condition such as severe daytime sleepiness.
- Wash your hair when you get home to remove any remaining electrode paste from your scalp.
- If your skin shows any redness where the sensors were attached, gentle moisturiser usually helps and it fades within a day or two.
- Resume your usual medications and diet immediately unless your doctor said otherwise.
- A sleep specialist reviews the recording, which typically takes several days to a couple of weeks depending on the facility.
- You will usually have a follow-up appointment to go through the results. Bring any questions you have about the findings.
- If sleep apnoea or another condition is confirmed, your doctor will discuss treatment options at that appointment, which may include a CPAP device, positional therapy, dental appliances, or other interventions.
- If you were tested to check how well your CPAP treatment is working, the results will guide any adjustment to the device settings.
Cost & What Determines It
The price of a polysomnography varies widely from one country and hospital to another, shaped by the level of technology used, how the night is staffed, and what is included in the package quoted to you.
- Type of study: a standard overnight recording costs less than a split-night study (where the first half diagnoses you and the second half tests a CPAP device) or a CPAP titration study (a full night spent finding the right pressure setting).
- Hospital class: a private hospital with an accredited, fully staffed sleep centre charges more than a public hospital sleep unit.
- Country of treatment: prices differ significantly between countries, even for the same equipment and level of expertise.
- Technologist staffing: some facilities have one technologist monitoring several patients; dedicated one-to-one overnight monitoring costs more.
- Number of channels recorded: a full-montage study recording many body signals costs more than a limited home-sleep-test alternative.
- Specialist interpretation fee: the sleep physician's fee for reading and reporting the study is sometimes included and sometimes billed separately.
- Additional investigations: if your referring doctor orders blood tests, respiratory function tests, or a daytime nap study (multiple sleep latency test) alongside the overnight recording, each adds to the total.
- Follow-up consultation: the appointment to discuss results may or may not be bundled into the quoted price.
Hospital packages often include the overnight room, sensor consumables, the recording itself, and sometimes the specialist's interpretation report. What is frequently billed separately includes the follow-up consultation, any additional daytime tests ordered after the night study, and, if treatment is recommended, the cost of a CPAP device or other equipment.
For Indonesian patients, BPJS Kesehatan and most Indonesian private insurance policies do not cover medical procedures performed abroad, so the full cost is usually paid out of pocket or through a private international health insurance plan that explicitly includes overseas treatment. Before travelling, ask the hospital for a written cost estimate that lists each item separately. This makes it easier to compare offers and to check exactly what your insurance, if any, will reimburse.
Frequently Asked Questions
Does a sleep study hurt?
A sleep study is painless. Technicians attach small sensors to your skin, scalp, and chest using a mild adhesive gel, and nothing punctures the skin. The sensors simply record your breathing, brain activity, and heart rhythm while you sleep.
How do I prepare for a sleep study, and do I need to fast beforehand?
Fasting is not required before a sleep study. Your care team will usually ask you to avoid caffeine and alcohol on the day of the test, wash your hair so the scalp sensors attach cleanly, and arrive at the sleep lab in the evening as you would on a normal night. Bring anything that helps you sleep, such as your own pillow or pajamas.
How long does a sleep study take, and when will I get the results?
The recording itself runs through a full night, usually seven to eight hours. A specialist called a sleep physician then reviews the data, which can take anywhere from a few days to about two weeks depending on the facility. Your referring doctor will walk you through what the results mean for your care.
How much does a sleep study cost?
The cost depends on whether the study is done in a hospital sleep lab or a clinic, the level of monitoring used, and the type of report your doctor requests. A written estimate from the hospital gives you the most accurate figure for your specific situation.
This page is general information, not a substitute for medical advice. Every case is different. Your doctor decides what is right for you.
