Experts say that while most trackers can in theory tell when a person is awake versus asleep, they are prone to mistakes. And as far as distinguishing sleep stages, trackers that include only an accelerometer as their sensor, "can't do what they claim," said Hawley Montgomery-Downs, a sleep researcher and associate professor at West Virginia University, who has studied the accuracy of sleep trackers. A persons sleep is usually evaluated through a scientifically structured sleep lab test, known as polysomnography.
In 2011, Montgomery-Downs and colleagues compared data from trackers to polysomnography tests, looking at adults who wore trackers while also undergoing an overnight sleep test. They found that the tracker overestimated the time participants were asleep by 67 minutes, on average.
"It says you are asleep more often than you accurately are," Montgomery-Downs said. The study also found that an actigraph, another device that also uses an accelerometer to monitor sleep and is sometimes used in sleep studies, overestimated sleep time by 43 minutes. Another study, presented at a sleep researchers' meeting in November 2013, found the opposite effect in children -the tracker underestimated how long the children were asleep by 109 minutes.
Although an accelerometer monitors your movement, "you move the same amount whether you're in deep sleep, or lighter stages of sleep," Montgomery-Downs said. Experts worry there may be a danger in consumers putting too much trust in these devices to accurately monitor sleep, especially users who have sleep disorders.
For people without sleep disorders, using a fitness monitor to track sleep isn't going to hurt or help them,
but if someone does present with a sleep disorder, tracking sleep with one of these monitors might give them a false reassurance. And sleep trackers with only an accelerometer cannot provide much insight into the quality of sleep. For instance, a person with sleep apnea may stop breathing 300 times a night, but this wouldn't be detected.
According To Dr. Jerald Simmons, a sleep study provides important information about what occurs during sleep and is designed to identify factors that cause sleep disruption. Typically, a study is done to identify breathing problems or limb movement problems during sleep. Once asleep, being hooked up to the wires does not prevent these types abnormal events from occurring. However, it is important that a person falls asleep during the test.It is important to mention that a sleep study is not designed to identify causes for difficulty falling asleep. If a person’s main sleep problem is difficulty falling asleep, treatment can be initiated without a sleep study, but does require a detailed assessment by a Medical Doctor, Nurse practitioner or Physician Assistant who understands the issues of Sleep Medicine.
CSMA's sleep centers throughout Greater Houston provide treatment to patients sufferering from snoring and obstructive sleep apnea disorders. For more information on how to stop snoring and obtain help for sleep apnea call us today at (281) 407-6222.
livescience.com: Fitness Trackers & Sleep: How Accurate Are They? -Rachael Rettner, January 20, 2014
huffingtonpost.com: fitness trackers and sleep