Table 5.

Odds ratio (95% CI) of incident obesity (n=3,786)^* and incident overweight + obesity (n=1,887)^† at phase 7 (2003–2004) across categories of sleep duration at phase 5 (1997–1999). The Whitehall II Study, London, England.

	≤5h	6h	7h	8h	≥9h	p-value*
Obesity (BMI ≥ 30)	18 cases / 243 subjects	90 cases / 1,229 subjects	101 cases / 1,668 subjects	34 cases / 593 subjects	3 cases / 53 subjects	Linear	Non-linear
Model 1	1.18 (0.70, 1.99)	1.22 (0.91, 1.64)	1	0.95 (0.64, 1.42)	0.88 (0.27, 2.88)	0.17	0.87
Model 2	1.14 (0.67, 1.93)	1.25 (0.93, 1.68)	1	0.90 (0.60, 1.36)	0.89 (0.27, 2.94)	0.12	0.72
Model 3	1.05 (0.60, 1.82)	1.21 (0.89, 1.64)	1	0.97 (0.64, 1.47)	0.91 (0.27, 3.01)	0.34	0.77
Overweight + Obesity (BMI ≥ 25)	31 cases / 114 subjects	132 cases / 567 subjects	185 cases / 847 subjects	61 cases / 331 subjects	7 cases / 28 subjects
Model 1	1.33 (0.85, 2.08)	1.09 (0.85, 1.41)	1	0.82 (0.59, 1.13)	1.29 (0.54, 3.10)	0.07	0.74
Model 2	1.32 (0.84, 2.09)	1.10 (0.85, 1.42)	1	0.81 (0.59, 1.13)	1.23 (0.51, 2.97)	0.07	0.80
Model 3	1.28 (0.80, 2.06)	1.09 (0.83, 1.41)	1	0.84 (0.60, 1.17)	1.29 (0.53, 3.14)	0.13	0.77

^*Number of non-obese participants at phase 5 (BMI < 30)

^†Number of normal-weight participants at phase 5 (BMI < 25)

^‡P-values for test of linear and non-linear trends

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