Recently I consulted on a case where a client with insomnia insisted on tracking her sleep with a wearable monitor (think Fitbit or Apple Watch). After using her device to log her sleep for the first few sessions of behavioral treatment for insomnia, she realized that her sleep tracker was actually increasing her anxiety about sleep. She became more aware of every toss and turn during the night and how it would be interpreted by the device. Ultimately, the client decided to forego the tracker and use only a paper sleep log each night and morning. Her anxiety decreased overnight (pun intended) and she starting falling asleep faster and staying asleep longer.
Obviously, discontinuing the use of her sleep tracker wasn’t the magic bullet that led this client’s sleep to improve; she was also implementing the behavioral techniques she learned in treatment. But the immediate decrease in sleep-related anxiety was notable and no doubt contributed to her improvements. It is a fascinating case example to me because, as an insomnia subject matter expert, I frequently get asked whether clients can use the data from their wearable sleep monitors, as opposed to using an old school sleep log. My colleagues and I consistently reply that sleep trackers are not helpful for insomnia, much to the chagrin of both clients and clinicians alike. But there is logic behind our recommendation, even beyond this clinical example.
One reason we recommend against the use of sleep trackers for our clients with insomnia is that they are not very accurate. The majority of data in device validation studies was collected from healthy individuals without a sleep disorder, limiting what we know about their accuracy for individuals with insomnia, among other sleep disorders. When individuals with insomnia have been included in studies, the results are not encouraging. In validation studies, researchers looked at how accurate sleep trackers are when compared with polysomnography (PSG, or what we commonly call a “sleep study”) performed on the same individuals. While wrist-worn trackers accurately tracked sleep 82% of the time for healthy sleepers, that number plummeted to 34% for individuals with insomnia (Baron et al, 2018). Wearable monitors tended to overestimate total sleep time and sleep onset latency, while underestimating how much time is spent awake during the night. They also had low accuracy when it came to identifying different stages of sleep (Lujan, 2021; Peake et al., 2018). Mobile-based apps that track sleep only through sensors on a smartphone performed even worse. (Baron et al). All sleep monitoring technology can also be affected by sharing your bed with a partner – human or pet – and the accuracy of wearable monitors can additionally be impacted by skin tone and tattoos (Lujan). So although the data collected from sleep tracker technology might be interesting, the precision of its data is impacted by many factors, including insomnia itself.
Even if these sleep monitors were more accurate in tracking sleep, they are not particularly relevant to the assessment and treatment of insomnia. In fact, when it comes to insomnia disorder, objective measurements of sleep carry little importance, whether they’re provided by a formal sleep study or a consumer sleep tracker. That’s because insomnia is a disorder of subjective dissatisfaction with sleep. You may have insomnia disorder whether you’re sleeping four hours every night or eight. Your subjective QUALITY of sleep is at least as important as your QUANTITY of sleep. So although external measurements may be able to tell you, with varying levels of accuracy, how much sleep you’re getting, no one but you can determine how refreshed you feel and how satisfied you are with your sleep.
Health monitoring consumer technology, including sleep trackers, can be enjoyable to use and may even motivate us to make healthy lifestyle choices. However, it’s problematic to confuse them with legitimate medical devices. Researchers note that although health-related technologies such as wearable trackers and smartphone apps are not labeled as medical devices, their marketing efforts implicitly suggest that they can provide accurate health data to help users identify problems and improve health. They may also contribute to obsessive rumination on health data and behaviors, as demonstrated by my clinical example (Peake et al., 2018). To be clear, I have no personal objection to these products. In fact, I still track every run and walk with my phone’s built-in fitness app and it keeps me motivated to go a little further each time (and to send
annoying motivating screenshots to my friends). If I’m bored enough, I even ask it to track my heart rate. But I wouldn’t treat my smartphone app as a substitute for a cardiac assessment, in the same way I think it’s a bad idea to rely on your sleep tracker for assessment or treatment of your insomnia. Not only will it provide you with unnecessary and unreliable data, but you may become even more worried about your sleep….which almost guarantees another night of tossing and turning.
The opinions in CDP Staff Perspective blogs are solely those of the author and do not necessarily reflect the opinion of the Uniformed Services University of the Health Science or the Department of Defense.
Carin Lefkowitz, Psy.D., is a clinical psychologist and Senior Military Behavioral Health Psychologist at the Center for Deployment Psychology (CDP) at the Uniformed Services University of the Health Sciences in Bethesda, Maryland.
Baron, K., Duffecy, J., Berendsen, M., Mason, I., Lattie, E., & Manalo, N. (2018). Feeling validated yet? A scoping review of the use of consumer-targeted wearable and mobile technology to measure and improve sleep. Sleep Medicine Reviews, 40, 151-159.
Lujan, M. (2021, March 25). Wearable technology using movement and heart rate for sleep-wake measurement: Basic principles, validity, and future directions. [Webinar]. University of Arizona College of Medicine. https://seminar.sleephealthresearch.com
Peake, J., Kerr, G., & Sullivan, J. (2018). A critical review of consumer wearables, mobile applications, and equipment for providing biofeedback, monitoring stress, and sleep in physically active populations. Frontiers in Physiology, 9. Doi: 10.3389/fphys.2018.00743