Table 3.

Prospective relationships^* of duration of sleep (hours) with changes in BMI and waist circumference between phase 5 (1997–1999) and phase 7 (2003–2004). The Whitehall II Study, London, England (n=4,378).

	≤5h (n=307)	6h (n=1,429)	7h (n=1,903)	8h (n=678)	≥9h (n=61)	p-value†
	Coef. (95% CI)	Coef. (95% CI)	reference	Coef. (95% CI)	Coef. (95% CI)	Linear	Non-linear
BMI (Kg/m2)
Model 1	0.02 (−0.17, 0.21)	0.02 (−0.09, 0.13)	0	0.08 (−0.06, 0.22)	−0.20 (−0.59, 0.20)	0.89	0.72
Model 2	0.01 (−0.18, 0.20)	0.03 (−0.08, 0.13)	0	0.08 (−0.06, 0.21)	−0.20 (−0.60, 0.20)	0.95	0.81
Model 3	−0.06 (−0.26, 0.14)	0.00 (−0.11, 0.11)	0	0.09 (−0.05, 0.23)	−0.17 (−0.58, 0.24)	0.36	0.82
Waist (Cm)
Model 1	0.56 (−0.08, 1.21)	0.14 (−0.22, 0.51)	0	0.14 (−0.33, 0.61)	−0.39 (−1.73, 0.96)	0.22	0.44
Model 2	0.58 (−0.07, 1.23)	0.16 (−0.20, 0.53)	0	0.11 (−0.37, 0.58)	−0.30 (−1.67, 1.07)	0.17	0.50
Model 3	0.44 (−0.23, 1.12)	0.12 (−0.26, 0.49)	0	0.15 (−0.33, 0.63)	−0.34 (−1.71, 1.03)	0.39	0.58

^*Results are expressed as β coefficients and 95% confidence intervals (CI) compared to 7h of sleep category

^†P-values for test of linear and nonlinear trends

Model 1: adjusted for age, sex, employment, and baseline value of BMI or waist

Model 2: Model 1 + alcohol consumption, smoking, physical activity and cardio-vascular drugs

Model 3: Model 2 + mental and physical scores (SF36), depressive symptoms and use of hypnotics