October 9, 2018/Brain & Nervous System

3 Reasons to Track Sleep on Your Smart Watch or Fitness Tracker

How data from your device can help you

Man wearing a fitness watch on his wrist while sleeping in bed.

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


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Are they worthwhile? “Yes, they are,” says sleep medicine expert Colleen Lance, MD.

“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.

When to consider tracking your sleep

Many people who rely on wearable technology 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, says Dr. Lance:

  1. You frequently wake up at nightEnvironmental 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 Fitbit®, Jawbone UP®, or Apple or Android watch and an FDA-approved medical device like the Actiwatch®.

“When researchers compared the Actiwatch to a formal sleep study, they found that it accurately measured total sleep and total wake time,” says Dr. Lance.

“The Actiwatch can also tell us when the sleep/wake cycle is off, which we look for in teens with insomnia.”

Because the Actiwatch can cost several thousand dollars, sleep study program often loan it to patients for testing.


Medical vs. commercial devices

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

In one American Academy of Sleep Medicine study, researchers had patients wear an Actiwatch along with several popular commercial wearables during a sleep study in the sleep lab.

“Overall, the commercial devices measured overall sleep time, and the amount of overnight sleep, pretty well,” says Dr. Lance. “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.

“Your smart watch or fitness device is also likely to overestimate sleep efficiency — the percentage of time you’re actually asleep while in bed,” she says.

Can wearables track light vs. deep sleep?

Some commercial wearables claim to track the time you’ll spend in light versus deep sleep. (You sleep deeply during the slow-wave and the REM, or rapid-eye-movement, stages of sleep.)

“During REM sleep, your brain catches up on its rest,” explains Dr. Lance. “During slow-wave sleep, your body catches up physiologically on its rest.”

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

“But even though not all wearable devices are FDA-approved, and not all of their data is great or validated, they are still useful,” she says. “We don’t want to throw the baby out with the bathwater.”

Web apps for mobile or desktop

If you don’t want to wear a wrist device, you can also download a sleep app on your smartphone, laptop, tablet or desktop computer.


Different sleep apps have different features. For example, with the Sleep by Cleveland Clinic app, you can assess your sleep disorders risk, learn useful strategies to sleep better and find out how to get expert help.

Many good apps are free or relatively inexpensive; reading product reviews can be helpful.

Will tracking make you anxious?

“There is one caveat: If you tend to be anxious, tracking your sleep may not be helpful,” cautions Dr. Lance.

Some people can become obsessed with their device, checking their data constantly and worrying about whether it’s normal to awaken during the night.

“But we all awaken at night,” she says. “The question is, do we fall back asleep OK, and can we function OK the next day?”

Wanting to track your biometric data, however, is generally a good thing, Dr. Lance believes. It means you’re more likely to follow doctor’s orders and do what it takes to maximize your well-being.

“Consumer sleep technologies offer a wonderful, relatively inexpensive way to become more engaged in your overall health,” she says.

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