How Data from Your Smart Bracelet can Help You

Suppose you need more sleep, or better sleep? Then you may be looking into wearable devices and apps that track sleep.

Are they worthwhile? Yes, they are. While digital apps and devices can’t replace formal testing, they can give your doctor a general idea of your total sleep time, your sleep/wake cycle and how disruptive your sleep may be. This can help your doctor decide whether to refer you to a sleep specialist or for a sleep study.

So, when to consider tracking your sleep?

Many people who rely on smart bracelet to count steps, or measure the miles they run or cycle, stumble upon the sleep-tracking function accidentally.

Here are three good reasons to track your sleep:

1. You frequently wake up at night. Environmental noise (think snoring partners and crying babies) can interrupt overnight sleep. Sleep disorders, such as obstructive sleep apnea or periodic limb movement disorder, can also wake you up frequently.
2. You’re too sleepy during the day. Insomnia and obstructive sleep apnea are the most common reasons for not getting enough sleep at night and feeling tired by day. Less common causes include narcolepsy, which robs you of normal REM sleep so that you nod off throughout the day.
3. You want to optimize your performance. If you compete as an athlete, or simply want to beat your personal best, a good night’s sleep will help you. Women approaching menopause may also want to optimize sleep to improve mood, memory and concentration.

How well do wearables work?

All wearable devices use an accelerometer to sense motion. (When you move, you’re awake; when you don’t, you’re asleep.) But there’s a big difference between your normal smart wristband and an FDA-approved medical device.

When researchers compared the medical device to a formal sleep study, they found that it accurately measured total sleep and total wake time. It can also tell people when the sleep/wake cycle is off, which doctors look for in people with insomnia.

But here is an issue that the pro medical device costs several thousand dollars, the average can not afford it. How about commercial smart bracelet?

How well do the affordable wrist-worn devices stack up against the medicals?

In one American study, researchers had patients wear an medical watch along with several popular commercial wearables during a sleep study in the sleep lab.

The result shows that the commercial devices measured overall sleep time, and the amount of overnight sleep, pretty well, but their accuracy dropped when measuring short naps during the day. It’s important to track the time you spend napping, because that can influence how well you sleep at night.

The research also shows that smart watch or fitness device may be also likely to overestimate sleep efficiency — the percentage of time people is actually asleep while in bed.

Can wearables track light vs. deep sleep?

Some commercial wearables claim to track the time you’ll spend in light & deep sleep. (You sleep deeply during the slow-wave and the REM, or rapid-eye-movement, stages of sleep.)During deep sleep your brain catches up on its rest, during slow-wave sleep, your body catches up physiologically on its rest.

But no device — not even the medicals — can track light or deep sleep very well the researcher said. If you want to track the stages of sleep, you’ll need to have EEG leads placed on your head in a sleep lab.

While even though not all wearable devices are FDA-approved, and not all of their data is great or validated, they are still useful, just like we don’t want to throw the baby out with the bathwater.