Can Wearable Technology Improve Your Sleep?

The key to getting a good night's sleep may not be in your bedroom, but on your smartphone or wearable fitness device.

Lack of sleep can affect your daily life -- whether it's at school or work, in personal relationships or regarding your health and safety. Untreated sleep problems can cause various health conditions such as high blood pressure, heart disease and stroke.

Sleep apps, fitness devices and online programs have become a popular way to help combat sleep issues. We've seen exponential growth in home-based monitoring technologies, particularly in consumer wearables (devices you wear) and nearables (devices that monitor from your nightstand, mattress or nearby). Many find that these tools can provide feedback and instruction that helps them get some shut eye. The information the technology provides can help you track your slumber and detect patterns that enable you to target areas for improvement.

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In addition, these devices provide a broad view of the larger population's sleep habits. For instance, the Fitbit longitudinal sleep database released information based on millions of nights their users logged in 2017. The data offered a glimpse of sleep behavior including average bedtimes, wake times and total hours slept. The average Fitbit user slumbered six hours and 38 minutes per night, a bit short of what sleep experts recommend. Interestingly, bedtime was inversely correlated with age. But while Generation Z went to bed the latest, they slept longer, putting their nightly average of total hours asleep on top. Baby Boomers slept the least, averaging six hours and 33 minutes per night.

Traditionally, sleep specialists have relied on more standard tests done in a clinical setting to measure sleep and diagnose sleep disorders. The gold standard is polysomnography, also called a sleep study, which records extensive data from surface sensors while you slumber in a sleep lab. Home sleep testing is a more limited study that looks solely at sleep apnea, although these devices often miss mild forms of the disease. Actigraphy is a medical grade accelerometer that has been used for decades to quantify total sleep and determine sleep wake patterns. The concept behind the use of an accelerometer is that activity correlates with wakefulness, while lack of motion correlates with sleep.

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With the recent explosion of consumer-facing digital tools marketed to measure sleep, many have turned to this convenient option for improving their sleep. Lots of people who rely on wearable fitness devices like the Apple Watch to count steps, or measure the miles they're running, have stumbled upon the device's sleep-tracking function.

Consumer sleep technologies are typically divided into "wearables" and "nearables." It's important to note that the majority of these are not Food and Drug Administration-approved medical devices. We're just starting to see validation studies in medical literature, and very few of those studies attempted to validate against the gold standard of polysomnography. There is also rapid turnover of the availability of these devices; as soon as one becomes known as a top-performer, the device or model is often no longer available.

Wearable devices typically use an accelerometer to sense motion, similar to actigraphy. Overall, the commercial fitness devices measure total sleep time and the amount of overnight sleep fairly well. But their accuracy drops when measuring short naps during the day. They also cannot track light or deep sleep very well. And your smart watch or fitness device is likely to overestimate sleep efficiency -- the percentage of time you're actually asleep while in bed.

People with difficulty sleeping or with sleep schedule irregularities might benefit from reviewing the data from these devices. The soon-to-be-released Withings ScanWatch is poised to be the first FDA-approved wearable to detect EKG abnormalities and sleep apnea.

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There are also new non-contact technologies called "nearables." These include smartphone apps or devices that detect snoring and changes in breathing. One such device, DROWZLE, received FDA approval to screen for obstructive sleep apnea. Nearables include mattress-based bedside radiofrequency biomotion sensors that provide low radiofrequency to detect motion while in bed. So far, the mattress-based devices have not performed well in validation studies in sleep-wake detection. Recent devices such as ResMed S+ and Withings Aura are near-the-bed devices that have held up in validation studies for the detection of sleep vs. wake.

This year promises to bridge the gap between consumer wearables/nearables and the more traditional diagnostic testing used for sleep disorders. Remote patient monitoring is gaining momentum among large hospital systems. In 2020, it's expected that reimbursement for FDA-approved RPM devices will increase.

In general, these technologies can help remove barriers between your home and local sleep lab, providing a better understanding of how you're actually sleeping (or not) in your own bed. While digital tools won't replace formal sleep testing, they can be a relatively inexpensive way to become more engaged in your overall sleep health and start a conversation with your health care provider about your ZZZs.

Nancy Foldvary, DO, MS, is director of the Cleveland Clinic Sleep Disorders Center.