Table 2.

Sleep quality metrics, measurement methods, and cutoff of good or poor sleep.

Clinical term, original term, and measurement method			Cutoff
Subjective sleep quality
	Pittsburgh Sleep Quality Index [31,38]	Good: ≤5 and poor: >5 [31]; good: ≤7 and poor: >7 [38]
	Sleep rating (SleepAsAndroid app) [20]	N/Aa
	Leeds Sleep Evaluation Questionnaire [19]	N/A
	Sleep rating (SleepApp) [19]	N/A
SEb
	SE (Fitbit) [33]	Good: ≥95% and poor: <95%
	Efficiency (MS Band) [43]	N/A
	SE (Polar) [40]	Good: >mean (SD) and poor: <mean (SD)
	SE (Garmin) [42]	Good: ≥85% and poor: <85%
SOLc (minutes)
	Minutes to fall asleep (Fitbit) [16]	N/A
	SOL (SleepAsAndroid app) [20]	N/A
	Sleep latency (Garmin) [42]	Good: ≤15, average: 15-30, and poor: >30
	Time to fall asleep (MS Band) [43]	N/A
Time at lights off
	Bedtime (Fitbit) [35]	Normal bedtime: median of a participant’s bedtimes; deviation categories were 1-30 minutes, 30-60 minutes, 1-2 hours, 2-3 hours, and ≥3 hours
	Bedtime (Fitbit) [37]	N/A
	Bedtime as estimated by the time of the last network signal [36]	N/A
Wake after sleep onset (minutes)
	Awake minutes (Garmin) [42]	Good: ≤20 and poor: >20
	Minutes awake (Fitbit) [16]	Good: ≤30 and poor: >30
Number of awakenings >5 minutes
	Awakenings >5 minutes (Garmin) [42]	Good: ≤1 and poor: >1
	Number of wakeups (MS Band) [43]	N/A
Time in bed (minutes)
	Time in bed (MS Band) [34]	N/A
Total sleep time (minutes)
	Minutes asleep (Fitbit) [16]	Good: 420-540 and poor: <420 or >540
Original metrics (no corresponding medical term)
	Sleep ratio=the ratio of the sleep minutes with normal heart rate versus total sleep time (Fitbit) [44]	Good: >90%, normal: 60%-90%, and bad: <60%
	Number of awakenings per hour [20]	N/A
	Awakening count including restlessness (Fitbit) [16]	N/A
	Permutation entropy of Fitbit measured sleep state time series [37]	N/A

^aN/A: not applicable.

^bSE: sleep efficiency.

^cSOL: sleep onset latency.