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. 2017 Mar 9;40(5):zsx043. doi: 10.1093/sleep/zsx043

Table 3.

Linear regression models of individual-level cortisol effect on actigraph-based sleep measures in Wave 2 of the National Social Life, Health and Aging Project (NSHAP), n = 672, adjusted for all listed covariatesa.

Variable Model 1 Model 2 Model 3
β p 95% CI β p 95% CI β p 95% CI
Average sleep fragmentation, % 0.02 .03 0.00 to 0.03 – – – – – –
Average WASO, hours – – – 0.27 .02 0.04 to 0.51 – – –
Average sleep duration, hours – – – – – – −0.01 .9 −0.08 to 0.07
Age 0.03 .002 0.01 to 0.04 0.03 .001 0.01 to 0.04 0.03 .001 0.01 to 0.04
Gender
 Maleb ref – – ref – – ref – –
 Female −0.41 <.001 −0.063 to −0.019 −0.43 <.001 −0.66 to −0.21 −0.44 <.001 −0.66 to −0.22
Race
 White, non-Hispanicb ref – – ref – – ref – –
 White, Hispanic 0.21 .4 −0.027 to 0.68 0.21 .4 −0.27 to 0.69 0.19 .4 −0.30 to 0.67
 African American, non-Hispanic −0.09 .6 −0.42 to 0.25 −0.08 .6 −0.42 to 0.26 −0.05 .8 −0.37 to 0.28
 Other 0.09 .6 −0.26 to 0.43 .11 0.5 −0.21 to 0.44 0.11 .5 −0.20 to 0.43
Education
 High school or equivalentb ref – – ref – – ref – –
 Less than high school −0.28 .1 −0.66 to 0.10 −0.33 .1 −0.71 to 0.05 −0.29 .1 −0.67 to 0.09
 Voc cert/some college/assoc −0.17 .3 −0.47 to 0.13 −0.17 .3 −0.47 to 0.13 −0.17 .2 −0.48 to 0.13
 Bachelors or more −0.14 .4 −0.47 to 0.19 −0.15 .4 −0.48 to 0.19 −0.18 .3 −0.51 to 0.16
Alcohol use
 Does not drinkb ref – – ref – – ref – –
 1–2 drinks/day 0.09 .5 −0.18 to 0.37 0.10 .5 −0.18 to 0.37 0.09 .5 −0.19 to 0.37
 3+ drinks/day 0.10 .5 −0.20 to 0.40 0.09 .5 −0.21 to 0.38 0.09 .5 −0.2 to 0.39
Tobacco use
 Nob ref – – ref – – ref – –
 Yes −0.03 .9 −0.37 to 0.31 −0.02 .9 −0.36 to 0.32 −0.02 .9 −0.37 to 0.32
Physical activity
 No physical activityb ref – – ref – – ref – –
 <3 time/month 0.25 .1 −0.06 to 0.55 0.23 .1 −0.07 to 0.53 0.22 .2 −0.09 to 0.52
 1+ times/week 0.14 .2 −0.06 to 0.33 0.13 .2 −0.08 to 0.33 0.10 .3 −0.10 to 0.31
Modified Charlson Comorbidity
 0b ref – – ref – – ref – –
 1–2 −0.02 .9 −0.33 to 0.29 −0.04 .8 −0.34 to 0.27 −0.06 .7 −0.36 to 0.23
 3+ 0.14 .4 −0.19 to 0.47 0.13 .5 −0.21 to 0.46 0.11 .5 −0.21 to 0.43
Depressive Symptomsc 0.00 .9 −0.03 to 0.03 0.00 .9 −0.03 to 0.03 0.01 .7 −0.02 to 0.03
Hormone replacement therapyd
 No ref – – ref – – ref – –
 Yes −0.19 .3 −0.54 to 0.15 −0.17 .3 −0.53 to 0.18 −0.19 .3 −0.55 to 0.17
Diurnal typee
 8 pm–1:59 am ref – – ref – – ref – –
 2 am–2:59 am 0.12 .5 −0.20 to 0.44 0.13 .4 −0.19 to 0.45 0.12 .5 −0.21 to 0.45
 3 am–8:59 am 0.19 .2 −0.13 to 0.50 0.21 .2 −0.12 to 0.52 0.20 .2 −0.13 to 0.52
Season
 Winter ref – – ref – – ref – –
 Spring 0.00 .9 −0.35 to 0.36 0.00 1.0 −0.35 to 0.36 0.01 1.0 −0.35 to 0.37
 Summer −0.25 .1 −0.60 to 0.10 −0.24 .2 −0.60 to 0.12 −0.26 .2 −0.61 to 0.10
 Autumn −0.38 .03 −0.72 to −0.04 −0.37 .04 −0.72 to −0.03 −0.39 .03 −0.72 to 0.04
Currently employed
 No ref – – ref – – ref – –
 Yes 0.10 .4 −0.13 to 0.33 0.10 .4 −0.12 to 0.33 0.09 .4 −0.14 to 0.32
 Constant 0.29 .4 −0.38 to 0.95 0.40 .2 −0.27 to 1.08 0.67 .2 −0.33 to 1.68

Abbreviations: WASO, wake after sleep onset; CES-D, Center for Epidemiological Studies-Depression; CI, confidence interval.

aThe three models each include one of the sleep measures and all covariates.

bReference group.

cAssesed utilizing a modified CES-D scale.

dAmong women only.

eDiurnal type was defined using the average midpoint of the sleep interval over the 3-day ancillary study period.