Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
Which Sleep Do These Trackers Monitor? | The Benefits of Wearing a Sleep Tracker
The Downfall of Sleep Trackers | A Wearable You Can Sleep On
In a world where you can use your fingertips to book a flight around the globe while simultaneously pacing back and forth across your room to get nearer to your 10,000 daily step goal, it shouldn’t be surprising that technology has been introduced to the world of sleep.
Sleep and fitness trackers have taken the world by storm in recent years. Wearables that come in wrist-watch-like bands and rings are being sported on the wrists and fingers of many.
Among the many functions of these comprehensive devices is their ability to shine a light on a metric that was once deemed difficult to monitor: your sleep.
However, the questions remain: are these trackers accurate, and can they help improve your sleep?
Which Sleep Do These Trackers Monitor?
Arguably, sleep plays one of the most integral roles in our physical and mental health: it determines our performance levels and impacts our everyday functioning.
Therefore, it’s essential to know how sleep is measured. Where traditionally, the gold-standard tool to measure sleep was polysomnography, nowadays, sleep measurement through fitness trackers has become the go-to thanks to their portability, cost-effectiveness, and proposed ability to measure the following sleep metrics:
- Sleep Duration: By tracking your heart rate and movements, certain wearables can determine when you fall asleep and when you wake up.
- Quality: Slightly more advanced wearables may come with apps that allow you to check the quality of your sleep, including whether or not you snore, if you wake up during the night, and, in some cases, whether you talk in your sleep.
- Sleep Stage: You’ve heard of REM sleep, light sleep, and deep sleep, but did you know when each occurs? Certain wearables have the technology to measure the stages of sleep you experience throughout the night, including how long you spend in each one.
- Lifestyle Tracking: Though admittedly not directly a sleep metric, some trackers offer various forms of lifestyle tracking, including activity levels, calorie consumption, and daily stress levels, all of which can influence your sleep.
Studies have demonstrated that these devices are effective at detecting sleep but not so much at detecting wakefulness. Likewise, it has been proven that though these wearables can measure different sleep stages, they do so somewhat inaccurately compared to polysomnography.
Many of the devices did prove to be a match for results procured using actigraphy, meaning that with a little extra performance testing and tweaking of certain elements, these devices can show promise in their validity against the gold standard polysomnography.
The Benefits of Wearing a Sleep Tracker
Despite studies showing that clinical polysomnography is superior to sleep-tracking wearables in terms of measuring sleep stage, these portable devices do have other significant benefits, including:
- Identify Sleep Disorders: Some sleep conditions may be difficult to diagnose, primarily because they affect you while you sleep. For those who don’t have a partner to let them know when their sleep is being disrupted, a sleep tracker may help identify sporadic awakenings throughout the night that could be a sign of sleep apnea, sleep fragmentation, or other sleep disorder that warrants attention.
- Correct Your Sleep Cycles: Depending on how good the technology is, some sleep trackers help you understand your sleep cycle better, giving you the insight you need to change things up if necessary.
- Maintain Your Well-Being: Included with the cost for most of these trackers is a friendly reminder that prompts you to move, drink water, and track your food intake. Though independently, these things seem rather bizarre, when combined, they can be used to determine to an extent how good your sleep will be.
The Downfall of Sleep Trackers
The main concern revolving around the accuracy of these devices is how they measure sleep. The wearables aren’t directly connected to your brain, as that would be an otherwise terrifying and frankly outrageous concept, so they can’t read your brainwaves.
Instead, they guess how much and well you sleep based on your habits, heart rate, and wake times. These variables aren’t direct metrics used to examine your sleep but are ones you can control to help improve your sleep going forward.[3,4,5]
A Wearable You Can Sleep On
Generally speaking, sleep trackers overestimate how long we sleep. However, despite this slight anomaly, getting into the habit of monitoring your sleep can be beneficial in rectifying your sleep issues.
Getting the recommended 7 hours of sleep each night is given for some people. For others, it’s a luxury. If you’re in the group that deems sleep a luxury, then a sleep tracker can help you recognize the factors affecting your sleep pattern and prompt you to seek help from a sleep specialist.
- Clement-Carbonell, V., Portilla-Tamarit, I., Rubio-Aparicio, M., & Sánchez-Romera, J. F. (2021). Sleep Quality, Mental and Physical Health: A Differential Relationship. International Journal of Environmental Research and Public Health, 18(2), 460. https://doi.org/10.3390/ijerph18020460
- Kim, K., Park, D. Y., Song, Y. S., Han, S., & Kim, H. (2021). Consumer-grade sleep trackers are still not up to par compared to polysomnography. Sleep and Breathing, 26(4), 1573–1582. https://doi.org/10.1007/s11325-021-02493-y
- Browne, J. D., Boland, D., Baum, J. T., Ikemiya, K. A., Harris, Q., Phillips, M., Neufeld, E., Gomez, D., Goldman, P., & Dolezal, B. A. (2021). Lifestyle Modification Using a Wearable Biometric Ring and Guided Feedback Improve Sleep and Exercise Behaviors: A 12-Month Randomized, Placebo-Controlled Study. Frontiers in Physiology, 12. https://doi.org/10.3389/fphys.2021.777874
- Chinoy, E. D., Cuellar, J. A., Huwa, K. E., Jameson, J. T., Watson, C., Bessman, S. C., Hirsch, D. A., Cooper, A., Drummond, S. P., & Markwald, R. R. (2021). Performance of seven consumer sleep-tracking devices compared with polysomnography. Sleep, 44(5). https://doi.org/10.1093/sleep/zsaa291
- Chinoy, E. D., Cuellar, J. A., Jameson, J. T., & Markwald, R. R. (2022). Performance of Four Commercial Wearable Sleep-Tracking Devices Tested Under Unrestricted Conditions at Home in Healthy Young Adults. Nature and Science of Sleep, Volume 14, 493–516. https://doi.org/10.2147/nss.s348795
- Liao, Y., Robertson, M. N., Winne, A., Wu, I. H., Le, T., Balachandran, D. D., & Basen-Engquist, K. (2021). Investigating the within-person relationships between activity levels and sleep duration using Fitbit data. Translational Behavioral Medicine, 11(2), 619–624. https://doi.org/10.1093/tbm/ibaa071