Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep MedicineJun 2, 2018

Testing the accuracy of a new wrist device for tracking sleep and wake times

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Apr 6, 2026

Abstract

Percent agreement with polysomnography for the new device was 91.3%.

The new wrist-worn device (myCadian) demonstrated a kappa statistic of 0.67, indicating a high level of agreement with polysomnography.
The commercially available actigraphy device (Actiwatch 2) had a lower kappa statistic of 0.50.
Positive predictive values for sleep epochs were 94.4% for the new device and 90.8% for the actigraphy device.
Both devices underestimated wake times and overestimated sleep durations compared to polysomnography.
Sleep latency was higher with the new device, while wake after sleep onset was higher with the actigraphy device.
Total sleep time and sleep efficiency were more comparable between the two devices.

Simplified

STUDY OBJECTIVES: To test the sleep-wake scoring reliability of a new wrist-worn sleep monitoring device.

METHODS: Twenty-seven adult good sleepers underwent 1 night of polysomnography (PSG) while wearing both the new device (myCadian [MC]; CurAegis Technologies, Rochester, New York, United States) and commercially available actigraphy (Actiwatch 2 [AW]; Philips Respironics, Murrysville, Pennsylvania, United States) on their nondominant wrist. PSG tests were manually stage scored. After excluding missing data, 20 participants had full-night data on all three devices with 17,734 total 30-second epochs. Using PSG as the gold standard, pooled epoch-by-epoch agreement for sleep and wake was calculated for each device using percent agreement and Cohen kappa statistic. Positive predictive values for both sleep and wake epochs, as well as sleep continuity statistics, were calculated.

RESULTS: Percent agreement with PSG-scored wake and sleep was 91.3% for MC (kappa = 0.67) and 87.7% for AW (kappa = 0.50). Positive predictive values for sleep epochs were 94.4% and 90.8% for MC and AW, respectively, and 74.5% and 65.6% for wake. Both devices underestimated wake and overestimated sleep compared to PSG. Descriptively, compared to PSG, sleep latency was higher with MC and wake after sleep onset higher with AW. Total sleep time and sleep efficiency were more similar across devices.

CONCLUSIONS: The kappa statistic for MC is consistent with a high level of agreement with PSG. Overall, the reliability of MC compared to PSG scoring was slightly more favorable than that of AW. Findings suggest that MC provides reliable sleep-wake scoring during a nocturnal sleep period for good sleepers.

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Testing the accuracy of a new wrist device for tracking sleep and wake times

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