Table 1. Nocturnal sleep-related variables, their definitions and descriptive data based on 24-h waist-worn accelerometer movement/non-movement data signals captured across all 12 ISCOLE country sites.

Variable	Definition	Mean±s.d. (range) across sites and range if applicable
Nocturnal sleep onset	The clock time of the first of 5 consecutive SIA-scored sleep minutes between the clock times of 1900 and 0559 hours	2218±0059 (1940–0307) hours
Nocturnal sleep offset	The clock time of the first minute of 20 consecutive minutes (between 2140 and 0459 hours) or 10 consecutive minutes (between 0500 and 1158 hours) scored as wake using SIA taken from the last sleep episode occurring during sleep period time	0707±0050 (0242–1109) hours
Midpoint	Mean clock time between nocturnal sleep onset and sleep offset; used to chronotype individuals as early or late sleepers (Table 2)	0243±0050 (2346–0626) hours
Sleep period time	Duration of time (minutes) from nocturnal sleep onset to nocturnal sleep offset, including all minutes scored as sleep/wake after onset using SIA	529.6±53.5 (316–809)
Sleep episode	Continuity of movement/non-movement patterns (⩾160 min) scored as SIA-defined sleep, including isolated SIA-scored minutes of wake, ends with the first of 10 consecutive minutes (between 0500 and 1158 hours) or 20 consecutive minutes (between 0940 and 0459 hours) of SIA-scored wake minutes	Frequency of nights with 1 sleep episode: 42 008 (91.7%) 2 sleep episodes: 3641 (7.9%) 3 sleep episodes: 172 (0.4%) 4 sleep episodes: 3 (0%)
Total sleep episode time (TSET)	Total minutes from all sleep episodes (including isolated wake minutes contained within sleep episodes) occurring during the sleep period time	529.0±53.7 (316–809)
Wake episode	An occurrence of ⩾20 consecutive SIA-scored wake minutes preceded and followed by a sleep episode; ends with 1 min classified as sleep	Frequency of nights with 0 wake episodes: 42 008 (91.7%) 1 wake episode: 3641 (7.9%) 2 wake episodes: 172 (0.4%) 3 wake episodes: 3 (0%)
Total wake episode time	Total minutes from all wake episodes occurring during TSET	0.6±4.0 (0–116.7)
Sleep episode efficiency	Total sleep episode time divided by sleep period time (expressed in %)	99.9±0.7% (78.7–100%)
Total restful (non-movement) sleep time	Accumulated minutes at 0 or <100 activity counts per minute during sleep episodes	Cutoff =0: 459.5±49.2 (237.6–764.3) Cutoff <100: 508.6±52.0 (301.2–797.3)
Sleep episode movements	Accumulated minutes >0 or ⩾100 activity counts per minute occurring during sleep episodes	Cutoff>0: 69.5±17.6 (9.3–164.8) Cutoff ⩾100: 20.4±7.6 (2.3–60.7)
Total disrupted sleep	Accumulated minutes >0 or ⩾100 activity counts per minute from all wake episodes plus activity-count defined sleep episode movements	Cutoff>0: 70.1±18.0 (9.3–164.8) Cutoff⩾100: 21.0±8.6 (2.3–128.9)
Restful sleep efficiency	Total restful sleep time at 0 or <100 activity counts per minute divided by sleep period time (expressed in %)	Cutoff=0: 86.8±3.1% (60.2–98.7%) Cutoff<100: 96.0±1.6% (76.5–99.5%)

Note: SIA denotes a Sadeh+inclinometer algorithm, described in detail in Barreira et al.¹²