How Accurate are Sleep Trackers?

Dr. Colleen Ehrnstrom's profile picture
Dr. Colleen Ehrnstrom, PhD
May 6, 20228 min read
Sleep trackers

As technology becomes more advanced, and tools like smartphones and fitness watches become better at collecting health data, more people than ever before have started tracking their sleep. In 2017, about 22% of women and 11% of men said they used sleep trackers regularly or occasionally to improve their rest. [1]

Sleep trackers may help you become more aware of your sleeping patterns and take note of any potential problems. However, many studies have found that they tend not to be very accurate in their measurements. There is also a risk that using these devices may actually lead to an unhealthy preoccupation with sleep that can contribute to insomnia.

How Do Sleep Trackers Work?

There are many types of devices that can track your sleep. They come with varying degrees of complexity — some sleep trackers may record a couple of different types of information, while others may paint a very detailed picture of how you slept at each point during the night. [2]

Some sleep trackers are wearable. They consist of devices that you put on your wrist, finger, or head. Wearable trackers stay in contact with your skin as they continually collect data. Many of these devices also gather information about your physical activity levels and calories consumed or burned.

Other sleep trackers are non-wearable devices. For example, you may collect sleep data with a sleep tracker app on your smartphone. In this case, you may place your phone on the bed next to you as you sleep. You can also use sleep monitors that sit on or under your mattress. Some of these devices may also report information about the conditions of your room, including temperature or humidity.

What Type of Information Do Sleep Trackers Collect?

Sleep trackers typically measure whether you’re asleep or not using metrics like your movements, heart rate, body temperature, and breathing patterns. All of these body processes undergo changes as you move through the different stages of sleep.

There are four sleep stages. During the first three stages, sleep starts out light and gets progressively deeper — it is deepest during stage 3 sleep. Your heart rate and body temperature decrease with each stage. The fourth sleep stage is rapid eye movement (REM) sleep, in which your heart rate increases, your breathing becomes more irregular, and you dream. [3]

Sleep trackers may use information like your heart rate to report that you were in a period of “light sleep” or “heavy sleep,” but this isn’t exactly the same as reporting your sleep stage. Studies have found that sleep trackers often can’t accurately detect which stage a person is in. [4]

The best way to measure your sleep stages is through tests like polysomnography that measure brain waves. You can’t go through these tests at home with sleep trackers; you undergo them in sleep clinics. Polysomnography and other tests administered by sleep specialists can help officially diagnose sleep disorders. [4]

How Accurate Are Sleep Trackers?

Sleep trackers aren’t perfect. Unfortunately, many companies don’t share exactly how their tracking programs work, which means it can be hard to determine their accuracy. Additionally, the vast majority of sleep trackers are categorized as “lifestyle/entertainment” devices. They aren’t regulated by the Food and Drug Administration (FDA), which means that no one is checking to make sure the devices are accurate or based on current scientific information.5

Multiple studies have found that sleep trackers aren’t as accurate as we might hope. Sleep trackers: [4], [6]

  • Are likely to report that you got more sleep than you really did
  • Are very inaccurate when it comes to measuring how long it takes for a person to fall asleep
  • Often incorrectly report that you’re sleeping when you’re actually awake, especially if you have chronic health conditions
  • Are poor at distinguishing how deep a person’s sleep is

Benefits of Sleep Trackers

Despite their limitations, sleep trackers may be helpful for some people. One benefit is that they can make you more aware of your sleep and encourage you to learn more about how to get better rest. [5]

Another positive is that they can give you a broad overview of your overall sleeping patterns. If you’re trying to develop good sleeping habits, such as going to bed and waking up at the same time each day, a sleep tracker can help you determine whether you’re on track. It may also point out other helpful insights — for example, you may notice that you get more sleep on days when you’ve been more physically active. [4]

A sleep tracker could also help you detect any overarching problems, such as being woken up early at the same time each day. It may also help you identify potential signs of sleep disorders. For example, loud snoring or waking up multiple times throughout the night could point to sleep apnea.

In the long term, sleep tracker data could also be combined with data from other health devices to help you and your doctor better understand your health.5

Negative Effects of Sleep Trackers

One problem with sleep trackers is their potential inaccuracy. People relying on these devices may think they’re getting more or less sleep than they really are. Additionally, the devices often can’t reliably tell what sleep stage you’re in, which means it’s hard to measure your sleep quality. [4]

Additionally, some people using trackers become so preoccupied with their sleep stats that they actually start getting worse sleep. Experts call this “orthosomnia.” For example, you may find that if your sleep tracker is regularly telling you that you’re not hitting your targets, you develop increased anxiety surrounding sleep. You may even be tempted to spend extra time in bed, which can worsen insomnia. [4]

Although sleep tracker devices and apps may provide you with a lot of data, they don’t always help you understand how to best use this information. For example, you may see that you’re not getting a lot of deep sleep, but feel unsure about how to change this — your sleep stages are largely outside of your control.

Instead, you may want to focus on what you can control, such as what time you lay down in bed and how long you spend trying to sleep. Sleep tracker devices may help, but aren’t strictly necessary when it comes to making these sorts of changes.

Conclusion

Sleep trackers can help define sleeping patterns and are a fantastic starting point to improve overall sleep. However, they may work best when paired with other strategies such as Cognitive Behavioral Therapy for Insomnia (CBT-I).4 During CBT-I, you work with a therapist or online program to adjust your behaviors and beliefs surrounding sleep. CBT-I is known to be very effective in treating insomnia. [7]

CBT-I can provide tailored one-on-one coaching that can teach you how to make the most of your sleep. For the most effective results, use your sleep tracker to start a conversation with your therapist.

To take the first step toward getting a better night’s sleep, learn more about CBT-I here or fill out our questionnaire to get matched with a sleep coach who can provide personalized advice.

References

  1. Statista. (2019, December 20). Percentage of U.S. adults that use apps to track their sleep as of 2017, by gender. https://www.statista.com/statistics/699434/us-adults-that-use-apps-to-track-sleep-by-gender/
  2. de Zambotti, M., Cellini, N., Goldstone, A., Colrain, I. M., & Baker, F. C. (2019). Wearable Sleep Technology in Clinical and Research Settings. Medicine and science in sports and exercise, 51(7), 1538–1557. https://doi.org/10.1249/MSS.0000000000001947
  3. Patel, A.K., Reddy, V., & Araujo, J.F. (2021, April 22). Physiology, Sleep Stages. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK526132/
  4. Baron, K. G., Abbott, S., Jao, N., Manalo, N., & Mullen, R. (2017). Orthosomnia: Are Some Patients Taking the Quantified Self Too Far?. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 13(2), 351–354. https://doi.org/10.5664/jcsm.6472
  5. Khosla, S., Deak, M. C., Gault, D., Goldstein, C. A., Hwang, D., Kwon, Y., O'Hearn, D., Schutte-Rodin, S., Yurcheshen, M., Rosen, I. M., Kirsch, D. B., Chervin, R. D., Carden, K. A., Ramar, K., Aurora, R. N., Kristo, D. A., Malhotra, R. K., Martin, J. L., Olson, E. J., Rosen, C. L., … American Academy of Sleep Medicine Board of Directors (2018). Consumer Sleep Technology: An American Academy of Sleep Medicine Position Statement. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 14(5), 877–880. https://doi.org/10.5664/jcsm.7128
  6. Conley, S., Knies, A., Batten, J., Ash, G., Miner, B., Hwang, Y., Jeon, S., & Redeker, N. S. (2019). Agreement between actigraphic and polysomnographic measures of sleep in adults with and without chronic conditions: A systematic review and meta-analysis. Sleep medicine reviews, 46, 151–160. https://doi.org/10.1016/j.smrv.2019.05.001
  7. Agency for Healthcare Research and Quality. (2017, August 1). Managing Insomnia Disorder. https://effectivehealthcare.ahrq.gov/products/insomnia/consumer



Dr. Colleen Ehrnstrom's profile picture
Dr. Colleen Ehrnstrom, PhD

Dr. Colleen Ehrnstrom is a licensed clinical psychologist with a specialty practice in Acceptance and Commitment Therapy (ACT). Areas of expertise include insomnia and other sleep disorders, anxiety, and depression.

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