What Is a Sleep Tracker and How Does It Work?
A sleep tracker uses movement, heart rate and sometimes other signals to estimate when you slept and how well. It is useful for patterns and habits, less so for sleep stages, and it cannot diagnose sleep disorders.
Key points
- How they work. Wearables use accelerometers and heart-rate sensors; under-mattress sensors use ballistic and movement signals.
- Accuracy. Total sleep time is estimated reasonably, while stage estimates are less reliable than laboratory sleep studies.
- Who benefits. People building routines or preparing for a clinic visit.
How they work
Wearables use accelerometers and heart-rate sensors; under-mattress sensors use ballistic and movement signals. Algorithms then estimate sleep and wake.
Accuracy
Total sleep time is estimated reasonably, while stage estimates are less reliable than laboratory sleep studies.
Who benefits
People building routines or preparing for a clinic visit. Anyone with symptoms of a sleep disorder needs a clinician, not a gadget.
Frequently asked questions
Is a tracker worth buying?
Only if the data will change what you do. Start with a free diary.
Are my data private?
Check the maker's policy before you sync.
Sources
- de Zambotti M, et al. Wearable sleep technology in clinical and research settings. Med Sci Sports Exerc 2019;51(7):1538–1557. PubMed
- Baron KG, et al. Orthosomnia: are some patients taking the quantified self too far? J Clin Sleep Med 2017;13(2):351–354. PubMed
Links go to PubMed searches for the paper title or to the official guideline or regulator page. Standards and regulations are revised, so check the current edition before relying on them. Mattress and pillow research is limited; treat findings as a starting point.
Go deeper
What Is Deep Sleep and How Is It Estimated?
Slow-wave sleep explained, how laboratories measure it and how wearables estimate it.
Read more →Sleep technologyHow Accurate Are Consumer Sleep Trackers?
What validation studies find: good at total sleep, weaker at stages and wake detection.
Read more →Sleep technologySmartwatch vs Dedicated Sleep Tracker: What Is the Difference?
Wrist watches, rings and under-mattress sensors compared on comfort, battery, accuracy and privacy.
Read more →Sleep technologyWhat Is REM Sleep?
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Read more →Sleep technologyAre Smart Mattresses Worth Buying?
What smart mattresses add (sensors, adjustable firmness, cooling) and whether the cost, repairs and privacy are worth it.
Read more →Keep reading
Sleep Technology: Trackers, Apps and Smart Devices Explained
What sleep trackers, apps and smart devices can and cannot tell you, with the evidence on accuracy and who benefits.
Read more →Sleep technologyHow Accurate Are Consumer Sleep Trackers?
What validation studies find: good at total sleep, weaker at stages and wake detection.
Read more →Sleep technologyHow to Understand Your Sleep Tracking Report
Read tracker reports calmly: what totals, stages, heart rate and scores mean and which to ignore.
Read more →Sleep technologyWhat Is Deep Sleep and How Is It Estimated?
Slow-wave sleep explained, how laboratories measure it and how wearables estimate it.
Read more →This article is general information, not medical advice. If you have persistent pain or sleep problems, please speak to a doctor.
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