Sleep Study
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Overview
A sleep study — formally polysomnography (PSG) — is a non-invasive overnight test that records your body’s signals during sleep. It is the standard test for diagnosing obstructive sleep apnoea, central sleep apnoea, and other sleep
disorders.
Loud snoring, daytime tiredness, morning headache, and pauses in breathing during sleep that others have noticed— these are the classic signs. Untreated sleep apnoea raises the long-term risk of heart attack, stroke, high blood pressure, and accidents from daytime sleepiness. It is treatable; the first step is the diagnosis.
What is this test?
You spend a night in our sleep lab. Several non-invasive sensors are attached to your head, chest, finger, and around the nose to record brain waves (EEG), eye movements, muscle activity, heart rhythm (ECG), breathing pattern, airflow, and oxygen levels.
All this is monitored throughout the night by a technician. The recording is then analysed in detail to count episodes of apnoea (pauses in breathing), drops in oxygen, and disturbances in sleep stages — together giving a clear picture of your sleep quality.
Why your doctor may order it
- Loud snoring with witnessed pauses in breathing
- Daytime sleepiness despite adequate hours in bed
- Morning headache, dry mouth, sore throat on waking
- Restless sleep, frequent waking
- Untreated high blood pressure that does not respond well to medication
- Heart conditions where sleep apnoea is suspected
- Suspected narcolepsy or other sleep disorders
- Before bariatric surgery in some patients
How long does it take?
You arrive in the evening, are set up over 30 to 60 minutes, and the recording continues through the night. You are usually free to leave by 7 to 8 the next morning. Total time at the hospital: approximately 12 hours, mostly spent asleep.
How to prepare
- Have a normal day, but avoid daytime naps if possible.
- Avoid caffeine (tea, coffee, cola) and alcohol from the afternoon onwards.
- Eat a light dinner — heavy meals can make it harder to sleep.
- Shower and wash your hair the evening of the study — clean, dry, product-free hair helps the sensors stick. Do not apply gel, oil, or styling product.
- Bring comfortable nightwear, toiletries, and anything you normally need for sleep (pillow, eye mask, book).
- Bring all medications you take routinely.
- Bring your prescription, ID, list of medicines, and any previous sleep reports.
- Plan to have a family member drop you off — you may feel groggy in the morning.
What to expect during the test
You arrive in the evening. The technician will go through what to expect, answer questions, and explain how to call for help during the night if needed. Sensors are gently attached with a paste or adhesive — they do not hurt. Wires run to a small monitor by the bed. You can move freely, get up to use the toilet, and turn in bed as usual. You go to sleep in a quiet, private room. A technician monitors your recording from another room throughout the night. Most people sleep more lightly than at home — this is normal and does not affect the diagnosis. In some cases, if significant sleep apnoea is detected partway through the night, a CPAP mask may be tried in the same session (“split-night study”). This will be discussed in advance.
After the test
- Sensors are removed in the morning. The sticky paste washes off in the shower.
- You can resume normal activities, but expect to feel a bit tired as you would after any disturbed night.
- The detailed analysis takes 5 to 10 working days. The sleep physician will explain the findings — most importantly the AHI (apnoea–hypopnoea index), which classifies sleep apnoea as mild, moderate, or severe.
- If sleep apnoea is confirmed, treatment options will be discussed — typically CPAP therapy, weight management, positional therapy, or in selected cases, dental devices or surgery.
Do's and Don'ts
- Stick to your normal bedtime routine where possible.
- Take your usual medications unless the team says otherwise.
- Bring your own pillow and comfortable nightwear.
- Tell the technician if you feel anxious — sleep is harder when you are worrying about sleeping.
- Wash your hair clean and product-free the evening of the study.
- Don't have caffeine or alcohol from the afternoon onwards.
- Don't take sleeping pills unless your doctor has specifically asked you to (they alter the recording).
- Don't worry about "not sleeping well" — most people sleep less than usual in a sleep lab, and that is okay.
- Don't apply hair gel, makeup, or lotion that interferes with the sensors.
- Don't drive home alone in the morning if you feel groggy.
Understanding your results
The sleep report classifies sleep apnoea by the AHI (apnoea–hypopnoea index): mild (5 to 15 events per hour), moderate (15 to 30), severe (over 30). The lowest oxygen level reached during the night is also reported. Sleep stages and any abnormalities of leg movement, brain waves, or heart rhythm are also analysed. Treatment recommendations follow the severity of the findings and your symptoms.
Frequently asked questions
Most people sleep less well than at home but enough for a reliable study. The wires are designed to be flexible and to allow turning. Even partial sleep gives useful results.
Yes — home sleep tests use fewer sensors and are suitable for many cases of suspected sleep apnoea. They are not as detailed as a lab study and are not appropriate for all patients. The team will recommend the right test for you.
If sleep apnoea is diagnosed, CPAP is usually the most effective treatment and is often used long-term. In selected cases, weight loss, positional changes, or surgery can reduce or eliminate the need. The decision depends on the severity and your situation.
Yes. Untreated sleep apnoea increases the risk of high blood pressure, heart attack, stroke, arrhythmias, accidents, and death. It is treatable — and treatment improves quality of life dramatically.
Not always. Snoring alone is common and often not dangerous. Snoring with witnessed pauses in breathing, or with daytime symptoms (tiredness, morning headache), needs assessment.