Apps and fitness trackers that measure sleep: Are they useful?

[Nelson Vergel]

In general, sleep tracking devices are fair to good at detecting sleep but poor at determining wakefulness. They are inaccurate for determining absolute sleep parameters (ie, total sleep time, sleep efficiency, wake time after sleep onset, and sleep onset latency) and in distinguishing the different sleep stages compared to polysomnography. Age-related differences have been found between consumer sleep devices compared with polysomnography and actigraphy-derived measures; because adults are likelier to lie still when awake, activity monitors are prone to overestimate sleep time in adults. Comparisons in patients with sleep apnea are conflicting.12,15 Claims that the “sensitive” mode may be appropriate for users with sleep disorders are thus far unsubstantiated.