Table 2. Two-level random intercept regressions investigating sex differences (0 = men, 1 = women) in sleep and load variables, based on data from 37 male and 19 female endurance athletes.
| DV | ICC | Est. men | S.E. men | Δ Est. women | S.E. women | p-value | R2 |
|---|---|---|---|---|---|---|---|
| Sleep variables | |||||||
| Time in bed (h) | .17 | 9.55 | .12 | .14 | .15 | .354 | 1.2% |
| Sleep onset latency (h) | .21 | .60 | .04 | -.06 | .07 | .433 | 1.2% |
| Total sleep time (h) | .17 | 7.37 | .08 | .51 | .11 | < .001 | 25.0% |
| Light sleep (h) | .18 | 4.19 | .07 | .22 | .09 | .013 | 8.4% |
| Light sleep (%) | .20 | 56.52 | .61 | -.75 | .85 | .377 | 1.2% |
| Deep/slow wave sleep (h) | .20 | 1.38 | .03 | .06 | .05 | .185 | 3.0% |
| Deep/slow wave sleep (%) | .18 | 21.51 | 1.07 | -.36 | .61 | .558 | .6% |
| REM sleep (h) | .16 | 1.81 | .03 | .23 | .05 | < .001 | 27.8% |
| REM sleep (%) | .14 | 24.25 | .36 | 1.32 | .49 | .007 | 10.2% |
| REM sleep latency (h) | .08 | 1.70 | .04 | -.27 | .06 | < .001 | 30.8% |
| Sleep efficiency (%) | .27 | 77.58 | .89 | 3.92 | 1.30 | .003 | 12.6% |
| Load | |||||||
| Mental strain (au) | .52 | 3.63 | .18 | -.20 | .35 | .562 | .7% |
| Total training load (TRIMP) | .10 | 106.80 | 4.72 | -8.47 | 8.26 | .305 | 2.3% |
| Subjective sleep quality | |||||||
| PSQI (au) | - | 3.11 | .34 | 1.10 | .58 | .057 | 6.1% |
REM = rapid eye movement; TRIMP = training impulse; PSQI = Pittsburgh Sleep Quality Index; DV = dependent variable; ICC = intra-class correlation; Est. = estimate; S.E. = standard error; R2 = explained variance in %. Regressions were clustered on participant. As only one data point of PSQI was available, the analysis with PSQI was a linear regression, not multilevel. ICC is therefore not provided. Values are unstandardized. Significant results are highlighted in bold.