O’Hare et al. reported the performance of three sleep monitoring devices for measuring sleep parameters in 20 normal subjects against sleep polysomnography (PSG) . The authors used two non-contact radio-frequency biomotion sensors, named SleepMinder® and SleepDesign®, and an accelerometer, named Actiwatch®. Compared with sleep PSG, all three devices overestimated total sleep time and underestimated wake after sleep onset and sleep onset latency. I appreciate that the authors checked the validity of three sleep monitoring devices, including Actiwatch®, against sleep PSG. Although the agreement of sleep/wake judgment by sleep monitoring devices is satisfactory for normal subjects, the authors recognized the limitation when these devices were applied for patients with insomnia. I have a query on their study with special emphasis on Actiwatch®.
O’Hare et al. quoted a paper on selecting appropriate cutoff point for sleep-wake judgment , but there is no definite way to determine the best sensitivity of sleep-wake judgment for every subject. Kushida et al. found the best overall accuracy and ability to detect wakefulness using Actiwatch® and PSG, when the “high-sensitivity” setting (20 counts per minute) was used . Peterson et al. adopted the default sensitivity setting (40 counts per minute), and they described the overestimation of total sleep time and underestimation of wake after sleep onset by Actiwatch® , which was the same study outcome by O’Hare et al.
There is a difference between brain activity and physical movement during sleep, and the discrepancy of sleep parameters between sleep PSG and sleep monitoring devices would be obvious for insomniacs . Validation study of sleep parameters by SleepMinder®, SleepDesign®, and Actiwatch® as a tool for sleep/wake judgment should also be conducted in patients with sleep apnea syndrome and other sleep disorders.
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Kawada, T. Validation study on sleep parameters by actigraphy for normal subjects. Sleep Breath 19, 11 (2015). https://doi.org/10.1007/s11325-014-0977-x
- Public Health
- Internal Medicine
- Cutoff Point
- Sleep Apnea
- Validation Study