Table 3.
Multilevel linear mixed models reveal the relationship between menstrual phase, covariates, and heart rate.
| Predictors | Model 1a | Model 2a | Model 3a,b | Model 4a,b | Model 5a | Model 6a | Model 7a | Model 8a,b | Model 9a | |
| Intercept | 58.40c (0.44) | 54.02c (2.86) | 58.58c (0.44) | 58.53c (0.44) | 58.60c (0.44) | 58.38c (0.44) | 60.37c (3.81) | 56.51c (0.58) | 53.52c (5.06) | |
| Cycle phase | ||||||||||
|
|
Menstrual | Reference group | Reference group | Reference group | Reference group | Reference group | Reference group | Reference group | Reference group | Reference group |
| Follicular | –1.57c (0.21) | –1.57c (0.21) | –1.29c (0.07) | –1.30c (0.07) | 1.57c (0.21) | –1.58c (0.22) | –1.55c (0.20) | –1.31c (0.07) | –1.62c (0.22) | |
| Fertile | –0.04 (0.25) | –0.03 (0.23) | 0.19d (0.07) | 0.19d (0.07) | –0.04 (0.25) | –0.04 (0.24) | –0.02 (0.24) | 0.19d (0.06) | –0.02 (0.24) | |
| Early luteal | 1.95c (0.19) | 1.98c (0.16) | 2.01c (0.06) | 2.01c (0.06) | 1.95c (0.18) | 1.98c (0.18) | 1.96c (0.17) | 2.01c (0.06) | 2.00c (0.17) | |
| Late luteal | 2.39c (0.24) | 2.40c (0.24) | 2.37c (0.07) | 2.37c (0.07) | 2.40c (0.24) | 2.41c (0.25) | 2.40c (0.24) | 2.37c (0.07) | 2.40c (0.25) | |
| Meald | ||||||||||
|
|
Small or no food | Reference group | —e | — | — | — | — | — | — | Reference group |
| Medium meal | 0.08 (0.06) | — | — | — | — | — | — | — | 0.05 (0.06) | |
| Large meal | 0.56c (0.07) | — | — | — | — | — | — | — | 0.31c (0.07) | |
| Body mass index (kg/m2) | — | 0.21 (0.12) | — | — | — | — | — | — | 0.20 (0.13) | |
| Coffeed | — | — | 0.02 (0.08) | — | — | — | — | — | –0.14 (0.08) | |
| Exercised | ||||||||||
|
|
No exercise | — | — | — | Reference group | — | — | — | — | Reference group |
| <60 min | — | — | — | 0.03 (0.06) | — | — | — | — | 0.05 (0.06) | |
| >60 min | — | — | — | 0.33c (0.07) | — | — | — | — | 0.36c (0.07) | |
| Sexual intercoursed | — | — | — | — | 0.03 (0.06) | — | — | — | –0.04 (0.06) | |
| Alcohold | ||||||||||
|
|
No alcohol | — | — | — | — | — | Reference group | — | — | Reference group |
| 1-4 units | — | — | — | — | — | 0.62c (0.05) | — | — | 0.53c (0.05) | |
| ≥5 units | — | — | — | — | — | 2.82c (0.15) | — | — | 2.70c (0.16) | |
| Age (years) | — | — | — | — | — | — | –0.05 (0.11) | — | –0.05 (0.12) | |
| Cycle duration | — | — | — | — | — | — |
|
0.07c (0.01) | 0.06c (0.01) | |
aUnstandardized b-coefficient values reported, with SEs in parentheses.
bThe model would not converge with the cross-classification term, so only random intercepts were included.
cP<.001 with a Bonferroni correction.
dP<.05 with a Bonferroni correction.
dWithin the 3 hours preceding the onset of sleep.
eIndicates a predictor was not considered in a given model.