Table 4.
Coefficients for Mean Sleep Time and Sleep Time Variability (IIV) Mediation Models with Body Mass Index as Outcomes
| Predictor | M (sleep duration) | M (sleep duration) | Y (BMI) | Y (BMI) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean sleep time–sleep duration pathway | IIV–sleep duration pathway | Mean sleep time–BMI pathway | IIV–BMI pathway | |||||||||
| Coefficient | SE | p | Coefficient | SE | p | Coefficient | SE | p | Coefficient | SE | p | |
| Constant | 594.29 | 74.72 | 0.000 | 391.52 | 15.90 | 0.000 | 49.66 | 9.85 | 0.000 | 41.56 | 4.52 | 0.000 |
| X (mean sleep time) | −0.16 | 0.05 | 0.002 | — | — | — | −0.00 | 0.01 | 0.547 | — | — | — |
| X (IIV) | — | — | — | −0.72 | 0.10 | 0.000 | — | — | — | 0.02 | 0.01 | 0.271 |
| M (sleep duration) | — | — | — | — | — | — | −0.02 | 0.01 | 0.016 | −0.02 | 0.01 | 0.156 |
| C1 education | 0.14 | 2.30 | 0.952 | 1.35 | 2.03 | 0.507 | −0.72 | 0.24 | 0.003 | −0.75 | 0.24 | 0.002 |
| R2 = 0.07 | R2 = 0.28 | R2 = 0.11 | R2 = 0.11 | |||||||||
| F(2, 129) = 4.85, p = 0.009 | F(2, 129) = 25.31, p ≤ 0.001 | F(3, 128) = 5.00, p = 0.003 | F(3, 128) = 5.32, p = 0.002 | |||||||||
p-Values in bold indicate a statistically significant effect.
IIV, IIV indicates sleep time variability which was calculated using intraindividual variability in sleep timing for each participants sleep start time.