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. Author manuscript; available in PMC: 2022 Dec 1.
Published in final edited form as: Sleep Health. 2021 Oct 9;7(6):699–707. doi: 10.1016/j.sleh.2021.08.005

Table 1.

Sleep variables, dimensions, and dichotomization rules. The Multi-Ethnic Study of Atherosclerosis, age <65 years (n=735).

Sleep variable Sleep health dimension Measure Dichotomization rule (coded as ‘1’) Sample prevalence of favorability (‘1’). n (%) Abbreviation

Midpoint variability (sd, min)d Regularityd Actigraphy <30 minutes 157 (21.4%) MPsd
Duration variability (sd, min)f Regularity Actigraphy <60 minutes 271 (36.9%) TSTsd
Quality (WHIIRS Likert subscale; higher is increasing complaints)d Satisfactiond Questionnaire “Sound and restful” or “very sound or restful” 267 (36.3%) Quality
Sleepinessd Alertnessd Questionnaire ≤10 617 (83.9%) ESS
Timing (midpoint)b,d Timingd Actigraphy 02:00–04:00b 466 (63.4%) Timing
Sleep maintenance efficiency (%)d Efficiencyd Actigraphy >90% 524 (71.3%) SME
Fragmentation Indexc Efficiency Actigraphy ≤15a 199 (27.1%) FI
Wake after sleep onset (min)f Efficiency Actigraphy ≤20 minutes 50 (6.8%) WASO
Total sleep timeb,d (min) Durationd Actigraphy 6–8 hoursb 461 (62.7%) TST
%Rb,e Architecture PSG 21%–30%b 251 (34.1%) % R
%N3b,e Architecture PSG 16%-20%b (50) 84 (11.4%) % N3
Apnea-Hypopnea Index (events/hr)e Obstructive sleep apnea PSG ≤15 events/hr 354 (48.2%) AHI
Sleep onset latency (difficulties initiating sleep – WHIIRS subscale)f Wake-sleep transition Questionnaire “Less than once a week” or “no, not in the past 4 weeks” 476 (64.8%) DIS
Sleep onset latency (min)g Wake-sleep transition Actigraphy - SOLact
a

WHIIRS: Women’s Health Initiative Insomnia Rating Scale. PSG: polysomnography. MPsd: midpoint standard deviation. TSTsd: total sleep time standard deviation. FI: the Fragmentation Index. TST: total sleep time. % N3: % non-rapid eye movement, stage 3 sleep. SME: sleep maintenance efficiency. AHI: the Apnea-Hypopnea Index. ESS: Epworth Sleepiness Scale. WASO: wake after sleep onset. % R: % rapid eye movement sleep.

b

These dimensions have optimal ranges in which overexpression of this dimension is considered problematic.

c

The cut-point for FI was defined as the nearest whole number to the most favorable quartile (lowest quartile).

d

Variables used in our operationalization of canonical Ru SATED (PC1)

e

In addition to Ru SATED (PC1), variables used in Ru SATED + OSA/Architecture (PC1)

f

In addition to Ru SATED + OSA/Architecture (PC1), variables used in the Sleep Health Score

g

Actigraphy-assessed onset latency used in all Principal Components-based sleep scores, in place of self-reported difficulties initiating sleep (see Appendix, and Table 3).