Table 2.

Adjusted hazard ratios for sleep duration at baseline (1993–1998) and mortality, the Singapore Chinese Health Study

Cause of death	Sleep duration at baseline
	≤5 hr	6 hr	7 hr	8 hr	≥9 hr
All-cause
No. of deaths	641	1285	1736	1514	434
Model 1†	1.14 (1.04–1.25)	0.99 (0.92–1.07)	1.00 (referent)	1.06 (0.98–1.13)	1.18 (1.06–1.31)
Model 2‡	1.12 (1.02–1.23)	0.99 (0.92–1.06)	1.00 (referent)	1.05 (0.98–1.12)	1.14 (1.03–1.27)
Cardiovascular
No. of deaths	191	380	538	449	132
Model 1†	1.11 (0.94–1.31)	0.95 (0.83–1.08)	1.00 (referent)	1.01 (0.89–1.15)	1.17 (0.96–1.41)
Model 2‡	1.08 (0.91–1.27)	0.95 (0.83–1.08)	1.00 (referent)	1.00 (0.88–1.14)	1.11 (0.92–1.34)
Ischemic heart disease
No. of deaths	95	224	289	254	65
Model 1†	1.06 (0.84–1.34)	1.06 (0.89–1.26)	1.00 (referent)	1.07 (0.90–1.26)	1.08 (0.83–1.42)
Model 2‡	1.03 (0.81–1.30)	1.05 (0.88–1.24)	1.00 (referent)	1.06 (0.89–1.25)	1.02 (0.77–1.33)
Stroke
No. of deaths	56	90	143	119	38
Model 1†	1.14 (0.83–1.56)	0.83 (0.63–1.08)	1.00 (referent)	1.01 (0.79–1.29)	1.24 (0.86–1.77)
Model 2‡	1.12 (0.82–1.53)	0.83 (0.64–1.08)	1.00 (referent)	1.00 (0.78–1.27)	1.19 (0.83–1.70)
Cancer
No. of deaths	226	465	611	554	133
Model 1†	1.22 (1.04–1.42)	1.04 (0.92–1.17)	1.00 (referent)	1.10 (0.98–1.24)	1.07 (0.89–1.29)
Model 2‡	1.22 (1.04–1.42)	1.04 (0.92–1.17)	1.00 (referent)	1.10 (0.98–1.24)	1.07 (0.88–1.29)

^†Model 1 adjusted for age (years), year of recruitment (1993–1995 and 1996–1998), gender, dialect group (Hokkien and Cantonese), physical activity (<0.5, 0.5–4, and ≥4 hr/week), level of education (no formal education, primary school, secondary school, or higher), smoking status (never, former, and current), alcohol intake (none, weekly, and daily), and body mass index (<20, 20–<24, 24–<28, and ≥28 kg/m²).

^‡Model 2 further adjusted for history of hypertension, ischaemic heart disease, stroke, diabetes, and cancer.