Table 1.

Within-individual variation in pre-bedtime light exposure is associated with objective sleep quality.

Wakefulness (minutes) in first 90 min after bedtime
Within and between individual light, adjusted for age, sex, and bedtime
Predictor	β	SE	t	Lower	Upper	p
Average light	− 0.42	0.62	− 0.69	− 1.64	0.79	0.49
Deviation from average light	0.89	0.09	9.88	0.71	1.07	< 0.00001
Age	− 0.03	0.01	− 2.59	− 0.046	− 0.006	0.01
Female sex	− 0.42	0.31	− 1.34	− 1.04	0.20	0.18
Average bedtime	0.55	0.49	1.13	− 0.41	1.52	0.26
Deviation from average bedtime	− 0.01	0.03	− 0.51	− 0.07	0.04	0.61

Generalized linear mixed model results for minutes of wakefulness in the first 90 min after bedtime, using a binomial distribution and logit link function. Predictors included age (years), sex, average light (log-transformed melanopic illuminance in 3 h before bedtime), deviation from average light (using log-transformed values), average bedtime (decimal hours), and deviation from average bedtime (hours). The table shows unstandardized coefficients (β), standard errors (SE), t value, Lower and Upper 95% confidence intervals, and p-values (significant values in bold).