The domain of sleep science using wearables has evolved by leaps and bounds in the past five years. The likes of Apple and Samsung have made considerable strides in using smartwatches and smart rings to track sleep patterns. And we’re not just talking about the amount of shut-eye you log on a daily basis, but also breakdowns of the various stages of sleep, such as deep sleep and REM.
Now, as per a large study by researchers at the University of California, San Francisco, and the University of California, San Diego, wearables might offer some clues about mental health as well. The research found that an irregular sleep-wake schedule is linked with more severe symptoms of depression, anxiety, and loneliness. So far, experts have largely focused on sleep quality and the number of hours you sleep each day, and less is known about how sticking to a regular sleep schedule is tied to mental health.
“Commercially available wearable devices pair with smartphone apps that provide behavioral advice to users, and therefore could both gather sleep regularity information and provide users with data-driven recommendations to increase sleep regularity, such as ideal bed and wake times,” the team notes in a paper published in the Scientific Reports journal.
For this study, the team collected sleep data from over 23,000 participants, who provided an average of 154 days of sleep data each. The average age of participants was 46, and they all wore a smart ring that tracked when they fell asleep and woke up, using the biosensing and motion data recorded by the wearable on their finger. This data helped the scientists calculate a Sleep Regularity Index (SRI) on a scale of 0 to 100, where a higher score means a person follows a more consistent sleep pattern. Participants also filled out a monthly self-reported survey about feelings of loneliness, anxiety, and depression.
In a press statement, the researchers noted that, overall, less regularly timed sleep is linked with more depression and anxiety. Participants with few or no symptoms of depression had an average SRI of 84. Those reporting mild depressive symptoms averaged 83, those with moderate symptoms averaged 81, and those with severe depressive symptoms averaged 75. In practical terms, an SRI of 84 means bedtimes and wake times shift by roughly an hour from day to day, while an SRI of 75 means shifts closer to an hour and a half.
When it comes to anxiety, an average SRI of 84 was associated with normal levels, while participants with severe anxiety averaged 79. Loneliness followed a similar pattern when studied against participants’ sleep-wake schedules. The experts note that the link between an irregular sleep-wake cycle and mental health problems could run both ways. A bad sleep schedule could be a symptom of poor mental health, but other research suggests it may come first and contribute to it.
So how can wearables come to the rescue? Well, sticking to a regular sleep schedule is worth a try, though this study didn’t test whether doing so actually eases symptoms of depression or anxiety. That’s something the researchers say future work should explore. Modern wearables not only track your sleep cycle, but also let you set schedules and reminders that nudge you when it’s time for bed. Moreover, their companion apps provide a detailed breakdown of your sleep patterns, including how many hours you slept, the average time you actually fell asleep, the quality of your sleep, and more.
“Taken together, these findings indicate that sleep regularity, as measured passively in the real world using a commercially available wearable device, is meaningfully associated with mental health,” writes the team behind the research. “Taken together, the results presented here align with prior data showing that improving sleep quality can improve mental health7 and highlight that the meaningful metric of sleep regularity can be easily accessed via widely available technologies (i.e., wearable devices). These findings have clinical and public health relevance, as people can understand and potentially modify their sleep regularity.”
Smartwatches from the likes of Apple and Samsung can even flag signs of sleep apnea, so that’s another perk. Broadly, if you are experiencing signs of anxiety or depression, the best way forward is to consult a certified healthcare professional. And if there is a link between these symptoms and your sleep cycle, wearables just might act as a supporting tool to help you keep an eye on your habits and self-assess.
