Fitbit’s trackers may not provide the most accurate calorie counts, but a new study shows they’re on their A-game for a different metric when users are fast asleep.
Wrist-worn devices such as fitness bands and smartwatches can determine sleep stages — from wake and light to deep and REM — “with a reasonable degree of accuracy” in healthy adult sleepers, according to a new study commissioned by Fitbit.
In the study, 60 adults — 36 male and 24 female, around the age of 34 (plus or minus 10 years) — were given three devices to wear during a traditional sleep stage study. Two fitness trackers were strapped to their left and right wrists and a Type III home sleep testing device, which has been recommended by doctors for conditions such as sleep apnea, was used as a tool to cross-reference and compare the results. The fitness trackers contained a 3D-accelerometer to record movement and an optical photoplethysmogram (PPG) to record cardiac activity.
Fitbit’s lead sleep research scientist, Dr. Conor Heneghan, said the performance of the fitness trackers were either similar to or better than previously reported results from non-electroencephalogram (EEG)-based sleep studies — studies that have in the past included combinations of cardiac, respiratory and movement trackers. EEG-based studies use of electrodes that track electrical activity in the brain and tend to be the most precise.
From the highest steppers to the best sleepers, you’re looking good, America! https://t.co/pMr9UhRQyF pic.twitter.com/0mTqWVMNMc
— Fitbit (@fitbit) May 31, 2017
The relative accuracy compared with alternative EEG methods may help healthcare professionals better analyze the sleeping habits of patients without having to place them in artificial sleep environments manufactured by laboratories — a more costly and less natural approach to sleep analysis, said Heneghan.
“Such a device could be useful in simplifying sleep research and in increasing public knowledge of sleep,” said Heneghan, who published the results in SLEEP, the official academic journal of the Sleep Research Society.
According to Fitbit, the study was scored and independently verified by two registered Polysomnographic (PSG) technicians, who used established guidelines by the American Academy of Sleep Medicine.
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Separately, Fitbit said it analyzed data from more than 4 billion nights of sleep stages across its treasure trove of user data and said its results supported long-standing sleep scientists’ theories.
Sleeping seven to eight hours a night is the most beneficial because it offers the highest combined percentage of time in deep and REM sleep stages. Waking up earlier than usual can impact the percentage of REM sleep a person gets because that stage tends to occur at the end of the night, according to Fitbit.
This study comes one week after researchers at Stanford University determined that fitness trackers, including Fitbit, tend to be extremely inaccurate at measuring calories.