Sleep, slumber, shuteye, Zzzs. Call it what you will, just make sure you stay on top of it. How much—and what kind of—sleep you get can affect your appetite, energy, weight, and recovery, not to mention protect against heart disease, diabetes, and cognitive decline. In other words, it’s pretty critical to your health and well-being. That’s why Fitbit is taking sleep tracking to the next level with Sleep Stages and Sleep Insights, two innovative new features that give you access to information previously only accessible in a sleep lab.
How Sleep Stages and Sleep Insights Work
Up until now, Fitbit’s manual and automatic sleep tracking used accelerometer data and machine learning algorithms to estimate how much time you spent asleep and awake each night. By taking more metrics into consideration—including continuous heart rate data—Fitbit was able to develop two new tools to help you better understand your sleep habits and how they compare to other people of your same age and gender. Here’s what they are and what they do:
Sleep Stages uses accelerometer data, heart rate variability (the time between beats), and proven algorithms to estimate how long you spend in light, deep, and REM sleep stages (as well as time awake) each night. Each stage is important, but for different reasons.
- Light Sleep (including sleep stages 1 and 2) occurs throughout the night and is important for memory, learning, and letting your body recover from the day; for most people it is 50-60 percent of your night.
- Deep Sleep (sleep stage 3) promotes a healthy immune system and muscle growth and repair; for most people it is 10-25 percent of your night (depending on age).
- Rapid Eye Movement (REM) Sleep is when most dreaming occurs and is important for mental recovery and memory formation; for most people it is 20-25 percent of your night. Most REM sleep comes at the end of the night, and is often the stage that’s cut short when your sleep duration decreases.
- Awake minutes (between 10-30 times per night) are a normal part of your sleep cycle each night, and is typically when your heart rate is more elevated during sleep.
Everyone’s sleep cycle is different, but by better knowing your sleep quality and patterns, and realizing the impact it has on your day, you can make lifestyle changes—such as diet, exercise, winding down before bed, and keeping a consistent sleep schedule—that can help improve your sleep over time. For more information, check out REM, Light Deep: How Much of Each Stage of Sleep Are You Getting?
For this feature, Fitbit uses the whole of your Fitbit data—everything from your diet to your exercise patterns—to discover trends about what may be affecting your sleep and then offer up personalized guidance on how to improve it.
For example, if you use a tracker that automatically tracks sleep, one insight may read: “You sleep a bit better on nights after a run. It’s subtle, but you spend 5 fewer minutes being restless/awake on those nights.”
Another potential insight could be: “Starting your day at a regular time helps lock in a stable circadian rhythm. This week you did a great job by having a consistent wake-up time!”
Sleep Insights relies heavily on your sleep logs, so the more you wear your tracker to bed, the more personalized insights you may receive. Hopefully, by better understanding your sleep patterns—and what affects them—you’ll be empowered to make lifestyle changes that can help improve your sleep (and overall health and wellbeing) over time.
How Fitbit Developed Sleep Stages and Sleep Insights
Over the past two years, Fitbit sleep scientists and product teams worked with industry-leading sleep experts from Johns Hopkins University, Stanford University, and the University of Arizona on everything from the design to the development of these features.
For Sleep Stages specifically, the Fitbit team conducted extensive internal testing by observing and analyzing several hundred nights of heart rate and movement data from volunteer sleepers while simultaneously comparing that to information gleaned from gold-standard lab equipment. They then used existing research on the connection between heart rate, movement, and sleep stages to develop an automated algorithm that could recognize and track each sleep stage.
Sleep Insights was developed by combining the current scientific understanding of sleep with Fitbit data gained from over 3 billion nights of logged sleep. Fitbit’s panel of sleep experts personally validated every insight that will be communicated to you, making sure the information is both applicable and scientifically valid.
Start Sleeping Better
Sleep Stages is available globally on Fitbit Alta HR, Charge 2, and Blaze. The feature is viewable in the Fitbit app—which is compatible with Android, iOS, and Windows devices—and on your Fitbit.com dashboard. Sleep Insights will be available in the Fitbit app and work with all Fitbit devices except Zip, which does not track sleep.
This article is not intended to substitute for informed medical advice. You should not use this information to diagnose or treat a health problem or condition. Always check with your doctor before changing your diet, altering your sleep habits, taking supplements, or starting a new fitness routine.