Table 2.

Annual change in walking speed and Short Physical Performance Battery by total sleeping time and time in bed

	Walking Speed				Short Physical Performance Battery
	N	β Estimate*	SE	P†	β Estimate*	SE	P†
Total Sleeping Time
≤ 6 h	311	−0.023	0.002	0.435	−0.289	0.023	0.211
7-8 h	371	−0.021	0.002	ref	−0.249	0.022	ref
≥ 9 h	69	−0.032	0.005	0.035	−0.335	0.051	0.119
Time in Bed
≤ 6 h	16	−0.027	0.010	0.440	−0.092	0.111	0.363
7-8 h	271	−0.019	0.002	ref	−0.195	0.024	ref
≥ 9 h	464	−0.025	0.002	0.027	−0.333	0.020	< 0.0001

^*Beta estimates for different groups are derived from linear mixed effect models and they indicate the average change in walking speed/SPPB score per year in that specific category.

^†P value indicates the significance of the difference between groups. SE, standard error. Models are adjusted for age, sex, education, physical activity, smoking, alcohol use, sleeping pills use, hypertension, coronary heart disease, diabetes, waist circumference, depression, C-reactive protein, interleukin-6, and tumor necrosis factor-α.