Fitbit's Heart Rate-Tracking Devices Accurately Measures Light, REM and Deep Sleep Stages

According to the recently concluded studies, Fitbit's wrist-worn heart rate-tracking devices was able to accurately track light, REM, and sleep stages.

Fitbit can accurate track sleep stages

Those devices include the Fitbit Alta HR, Fitbit Blaze, and Fitbit Charge 2 wrist-worn trackers that incorporate movement and cardiac sensor. Fitbit’s study, which were scored independently by polysomnography technicians showed that these devices can be used to track sleep stages with a reasonable degree of accuracy in normal adult sleepers, avoiding the cost and artificial sleep environment of a sleep laboratory.

Moreover, analysis of over 4 billion nights of Fitbit sleep data supports scientific theories that sleeping 7+ hours can positively affect sleep quality.

With our sleep tracking tools, Fitbit has transformed what people can learn about their sleep habits by taking the ability to track sleep stages out of a lab and putting it on the wrist,” said Dr. Heneghan. “The ability to easily track your sleep not only helps individuals better understand their own sleep, it also unlocks significant potential for us to better understand population health and gain new insights into the mysteries of sleep and its connection to a variety of health conditions.

As a quick recap, Fitbit introduced new sleep features to provide people with a greater understanding of their sleep habits last April of 2017. Sleep Stages, now available with Alta HR, Blaze and Charge 2, which uses heart rate variability to estimate the amount of time spent in light, deep and REM sleep. It also measures time awake each night to help better recognize sleep quality.

Here's some of Fitbit's analysis and observation

• While sleeping longer will lead to getting more deep and REM sleep, sleeping 7-8 hours gives you the highest combined percentage of time in these stages. Sleeping less than 7 hours will lead to deep and REM stages being a smaller proportion of your overall sleep.
• Waking up earlier than usual can impact the percentage of REM sleep you get, which occurs more at the end of the night.
• When getting five hours or less of sleep a night, users get a smaller percentage of deep sleep, which occurs near the beginning of the night. Deep sleep is important for many physical processes such as cell regeneration, human growth hormone secretion and feeling refreshed in the morning.
• People are unconsciously awake at night; the average awake time adds up to 55 minutes, or 10-15% of the night. Short periods of awake time are a normal component of a healthy sleep cycle.

Sleep pattern key findings by gender and generation

Sleep pattern data

• Gen Z (age 13-22) sleeps the most, averaging 6 hours and 57 minutes of sleep a night with 17% of the time in deep sleep, while Baby Boomers (age 52-71) sleep the least at 6 hours and 33 minutes per night with 13% of the time in deep sleep.
• People get less deep sleep as they age, decreasing from an average of 17% at age 20 to 12% at age 70.
• Women sleep an average of 25 more minutes a night than men and have a higher percentage of REM sleep, a difference which increases even further around age 50.

These findings further support the general recommendation that most adults need to consistently sleep 7-9 hours per night, and illustrate why a good night’s rest is so important for your overall wellbeing,” said Dr. Michael T. Smith, Jr., professor of Psychiatry, Neurology and Nursing at Johns Hopkins University School of Medicine and Fitbit Advisory Panel Sleep Expert. “When sleeping less than seven hours, your body may not be getting enough of both deep and REM sleep, the two sleep stages that are very important to many aspects of maintaining your overall health.

Overall, the study showed that high quality of sleep is needed to stay healthy.