Measuring Sleep Quality and Efficiency With an Activity Monitoring Device in Comparison to Polysomnography

Background: Monitoring for physical activity becomes popular and actually many devices are available. Some physical activity monitors (PAMs) provide data about sleep quality for the user, but there are scarce data concerning validity and usability of these measurements. This study compared the data of sleep parameters generated by a PAM with the polysomnography (PSG).

Methods: In 2016, data of 26 patients in two consecutive PSGs as well as in two daytime and nighttime measurements with a PAM according to physical activity and sleep quality were collected. Furthermore, sleep quality, using the Pittsburgh sleep quality index (PSQI), daytime fatigue, using the multidimensional fatigue inventory (MFI-20) and additionally data of a sleep diary were collected.

Results: There were positive correlations of both methods with respect to total sleep time (TST) (r = 0.76, P < 0.01) and sleep efficiency (r = 0.71, P < 0.01). Data analysis over two nights showed that over 90% of the TST (95% confidence interval (CI) -1.59 to 0.82) and of the sleep efficiency (95% CI -8.28 to 15.51) were within the limits of agreement. The analysis of the PSQI and the sleep efficiency of the PAM showed no significant correlations. The daytime fatigue correlated negatively with the physical activity (r = -0.72, P < 0.01).

Conclusion: The sleep efficiency and TST measured with the PAM sufficiently reflect the PSG sleep parameters and the subjects' subjective feelings. At the same time, PAM results are also correlated with the subjectively perceived quality of sleep. Further investigations to assess the long-term results are pending.