Table 4.

Odds ratio (95% CI) of prevalent obesity and overweight + obesity across categories of sleep duration at phase 5 (1997–1999). The Whitehall II Study, London, England (n=5,021).

	≤5h (n=380)	6h (n=1,650)	7h (n=2,153)	8h (n=774)	≥9h (n=64)	p-value*
Obesity (BMI ≥ 30)	88 cases	238 cases	259 cases	97 cases	9 cases	Linear	Non-linear
Model 1	2.02† (1.53, 2.66)	1.20 (0.99, 1.45)	1	1.01 (0.78, 1.30)	1.08 (0.53, 2.22)	<0.001	0.01
Model 2	1.88† (1.41, 2.49)	1.24† (1.02, 1.51)	1	1.03 (0.79, 1.33)	0.99 (0.48, 2.08)	<0.001	0.06
Model 3	1.65† (1.22, 2.24)	1.23† (1.01, 1.50)	1	1.02 (0.78, 1.33)	0.89 (0.42, 1.90)	0.003	0.30
Overweight + Obesity (BMI ≥ 25)	245 cases	1,004 cases	1,198 cases	392 cases	35 cases
Model 1	1.45† (1.15, 1.82)	1.25† (1.10, 1.43)	1	0.80† (0.67, 0.94)	0.97 (0.59, 1.60)	<0.001	0.36
Model 2	1.38† (1.09, 1.74)	1.27† (1.11, 1.46)	1	0.80† (0.67, 0.95)	0.86 (0.51, 1.44)	<0.001	0.35
Model 3	1.41† (1.10, 1.80)	1.28† (1.12, 1.47)	1	0.82† (0.69, 0.98)	0.82 (0.48, 1.39)	<0.001	0.49

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

^†Significant p-values (p ≤ 0.05) for contrast of that specific category versus reference category

Model 1: adjusted for age, sex, employment

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