Working to fit a sleep lab in a sensor

Our heart rate sensors and motion detectors work behind the scenes to track your sleep. Just wear your tracker or watch to bed, let Fitbit work its magic, then see your sleep stats and insights right in the app.

Use your heart to reveal the quality of your ZZZs

Fitbit trackers and watches use your sleeping heart rate, movement and more to measure your time spent in each sleep stage and give you a personalized Sleep Score that shows how well you slept. Plus, view your trends over time in the app, and see how your stats compare to others.*

Uncover the power of light, deep & REM sleep

Each night your body cycles through different sleep stages based on your heart rate, and getting enough time in each one is key to feeling refreshed. Light sleep strengthens memory and learning. Deep enables physical recovery. REM helps with strategic thinking and creativity.

Reaching the recommended activity guidelines

Active Zone Minutes counts your time spent in any heart-pumping activity. Your default goal is based on the widely accepted recommendation of 150 minutes of moderate activity or 75 minutes of vigorous activity per week.**

Work out smarter

With Active Zone Minutes, the harder you work, the more credit you get. 1 minute in the fat burn zone earns 1 Active Zone Minute, and 1 minute in the cardio or peak zone earns 2 Active Zone Minutes. You put in the work, and we’ll do the math!

A focus on personalization

Your target heart rate zones are personalized based on your age and resting heart rate, giving you a more accurate understanding of how to optimize your effort.

Zone notifications keep you in the know

When you’re in an exercise mode, your Fitbit tracker or watch buzzes to let you know when you enter and exit a heart rate zone: 1 buzz for the fat burn zone, 2 buzzes for the cardio zone and 3 buzzes for the peak zone.

Heart rate tracking made for every day

In the past, heart rate tracking was expensive, awkward and uncomfortable. With the invention of PurePulse, we made it accessible to anyone. Inspired by a thimble-sized sensor used in hospitals, we conducted extensive research to make wrist-based heart rate tracking work in all types of environments.

Photoplethysmography: a long word with a short explanation

We use light to measure blood flow. A sensor shines a green light onto the skin, and light detectors called photodiodes measure how much light is being absorbed. This tells you how many times your heart is beating per minute.

Innovation backed by research

In a number of external studies worldwide, PurePulse™ technology has surpassed industry expectations. And over 50 patents related to PurePulse™ technology have been awarded to Fitbit’s heart rate innovation in the process.