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. 2021 Feb 18;23(2):e23936. doi: 10.2196/23936

Table 2.

Distribution of sleep metrics obtained from the Fitbit as well as weekly averages of the same for all sleep sessions preceding the cognitive tasks.

Distribution of sleep metrics N Minimum Maximum Mean (SD)
Previous night’s sleep metrics




Sleep duration (minutes) 556 180.0 761.0 433.12 (87.47)

REMa sleep (%) 556 2.8 34.25 18.18 (5.32)

Light sleep (%) 556 30.04 73.71 52.92 (6.95)

Deep sleep (%) 556 0.0 33.57 15.92 (5.1)

Duration of REM sleep (minutes) 556 6.0 190.0 79.24 (29.04)

Duration of light sleep (minutes) 556 79.0 429.0 228.98 (54.13)

Duration of deep sleep (minutes) 556 0.0 157.0 68.69 (25.12)

Number of awake periods >5 minutes 556 0.0 8.0 3.03 (1.33)

Sleep efficiency (out of 100) 556 27 100 89.6 (14.11)

Sleep debt 556 –0.81 0.55 0.0 (0.18)

Sleep shift 556 –425.04 1199.21 7.1 (122.18)
Sleep metrics over last 1 week




Average sleep duration (minutes) 556 221.0 564.25 433.27 (50.53)

Average REM sleep duration (minutes) 556 23.0 163.0 78.94 (15.59)

Average light sleep duration (minutes) 556 84.0 310.2 228.67 (36.2)

Average deep sleep duration (minutes) 556 28.0 123.5 69.14 (15.86)

Average sleep debt 556 –0.17 0.19 0.0 (0.06)

Average sleep shift 556 –311.47 202.93 6.97 (62.04)

aREM: rapid eye movement.