Table 4. Mean differences of the sleep parameters in minutes and means of sensitivities to sleep, specificity for sleep, and agreement assessed by the wearables compared to polysomnography.

Variable	FitbitCharge 4	GarminVivosmart 4	WHOOP
TSTa (min)	5.7	46.9	−1.4
LSb (min)	37.6	27.9	−9.6
DSc (min)	−19.2	23.5	−9.3
REMd sleep (min)	4.0	−12.5	21.0
Sensitivity to sleep (%)	91.2	98.0	91.7
Sensitivity to LS (%)	N/Ae	60.0	60.0
Sensitivity to DS (%)	75.0	45.0	65.0
Sensitivity to REM sleep (%)	86.5	34.0	67.0
Specificity for sleep (%)	61.3	30.0	55.7
Agreement (%)	N/A	48	62
Cohen κ	N/A	0.20	0.46
Papers, n	3	2	4

^aTST: total sleep time.

^bLS: light sleep.

^cDS: deep sleep.

^dREM: rapid eye movement.

^eN/A: not applicable.