The main methods
Polysomnography (in-laboratory sleep study)
The most detailed option. Sensors record brain activity (EEG), eye movement, muscle tone, airflow, chest and abdominal effort, oxygen saturation, heart rhythm and leg movements. It is the only method that reliably measures sleep stages and is used for complex cases or when other sleep disorders are suspected.
Home sleep apnoea testing
A simplified overnight recording worn in your own bed — usually airflow, breathing effort, oxygen saturation and pulse. Comfortable, widely used, and well suited to straightforward suspected obstructive sleep apnoea. More detail in our guide to sleep apnoea testing.
Overnight pulse oximetry
A fingertip sensor records oxygen saturation and pulse through the night. It can show repeated dips in oxygen suggestive of breathing events, but it cannot distinguish between causes on its own.
Wearables and phone apps
Watches, rings and bedside sensors estimate sleep from movement, heart rate and sometimes sound or oxygen. Best treated as trend indicators for your own habits rather than measurements.
Sleep diaries
Deliberately low-tech and still recommended by sleep clinicians. Recording bedtime, wake time, awakenings, caffeine and alcohol reveals patterns no device can infer.
What the numbers mean
- Total sleep time — how long you were actually asleep, not time in bed
- Sleep efficiency — sleep time as a percentage of time in bed
- Awakenings — how fragmented the night was
- Oxygen saturation (SpO₂) — how well blood oxygen was maintained
- AHI — breathing events per hour, reported by clinical tests only
Using sleep monitoring well
- Compare weekly averages, not individual nights
- Change one habit at a time so you can see what actually helped
- Keep sleep and wake times consistent, including at weekends
- Record daytime sleepiness too — it is often the most meaningful outcome
- Avoid checking a tracker anxiously at 3am; it worsens sleep more often than it helps
When to seek clinical assessment
Speak to your GP if you have loud snoring with witnessed pauses in breathing, significant daytime sleepiness, morning headaches, repeated night waking to pass urine, or if you ever feel sleepy while driving. Consumer sleep monitoring is not a substitute for that conversation.
Frequently asked questions
What is overnight sleep monitoring?
Overnight sleep monitoring is the recording of physiological signals during sleep — typically airflow, breathing effort, oxygen saturation, heart rate and sometimes brain activity — to understand sleep quality and detect disorders such as sleep apnoea.
Are sleep tracking watches accurate?
Consumer wearables are reasonably good at estimating total sleep time and broad patterns, and less reliable at sleep staging. They are useful for spotting trends and building habits, but they are not diagnostic instruments.
How long should I monitor my sleep before drawing conclusions?
Single nights vary enormously. Two to four weeks of consistent recording gives a far more meaningful picture of your typical sleep than any one night.
Can sleep monitoring detect sleep apnoea?
Clinical home sleep apnoea tests and in-lab studies can. General consumer sleep trackers may flag suggestive signs such as snoring or oxygen dips, but only a sleep service can diagnose the condition.