Table 5.
Hazard ratios for all-cause mortality in relation to self-reported sleep duration by several characteristics among 135,685 men and women in the Multiethnic Cohort Study, 1993-2007a
| Variable | No. Deaths | Daily sleeping |
P intb | ||||
|---|---|---|---|---|---|---|---|
| ≤5 hr |
6 hr |
7 hr |
8 hr |
≥9 hr |
|||
| HR (95% CI) | HR (95% CI) | HR | HR (95% CI) | HR (95% CI) | |||
| Ethnicity | 0.34 | ||||||
| White | 4,417 | 1.30 (1.14-1.48) | 1.07 (0.98-1.17) | 1.00 | 1.07 (0.99-1.16) | 1.26 (1.14-1.38) | |
| African American | 4,391 | 1.06 (0.96-1.17) | 1.01 (0.93-1.10) | 1.00 | 0.99 (0.91-1.08) | 1.17 (1.06-1.30) | |
| Native Hawaiian | 1,515 | 1.22 (1.04-1.44) | 0.96 (0.83-1.11) | 1.00 | 1.10 (0.95-1.28) | 1.26 (1.05-1.51) | |
| Japanese American | 5,110 | 1.11 (1.00-1.23) | 1.09 (1.01-1.17) | 1.00 | 1.09 (1.01-1.18) | 1.23 (1.10-1.37) | |
| Latino | 3,902 | 1.10 (0.98-1.24) | 1.01 (0.93-1.11) | 1.00 | 1.01 (0.92-1.09) | 1.12 (1.01-1.25) | |
| Age at enrollment | 0.89 | ||||||
| 45-64 | 8,145 | 1.17 (1.08-1.26) | 1.05 (0.99-1.12) | 1.00 | 1.02 (0.96-1.09) | 1.23 (1.14-1.33) | |
| 65-69 | 4,746 | 1.13 (1.02-1.26) | 1.07 (0.98-1.16) | 1.00 | 1.05 (0.97-1.13) | 1.25 (1.14-1.38) | |
| 70+ | 6,444 | 1.09 (0.99-1.19) | 1.02 (0.95-1.09) | 1.00 | 1.07 (1.00-1.14) | 1.14 (1.05-1.24) | |
| Education | 0.14 | ||||||
| High school or some college | 15,447 | 1.12 (1.06-1.19) | 1.05 (1.00-1.10) | 1.00 | 1.03 (0.99-1.08) | 1.19 (1.13-1.26) | |
| College graduate/postgraduate | 3,836 | 1.21 (1.06-1.37) | 1.03 (0.95-1.13) | 1.00 | 1.10 (1.01-1.20) | 1.23 (1.10-1.38) | |
| Diabetes | 0.31 | ||||||
| Yes | 3,858 | 1.09 (0.97-1.22) | 1.00 (0.91-1.10) | 1.00 | 1.06 (0.97-1.15) | 1.30 (1.17-1.44) | |
| No | 15,477 | 1.15 (1.09-1.22) | 1.06 (1.01-1.10) | 1.00 | 1.04 (1.00-1.09) | 1.17 (1.11-1.24) | |
| Hypertension | 0.99 | ||||||
| Yes | 9,483 | 1.17 (1.09-1.25) | 1.04 (0.99-1.11) | 1.00 | 1.05 (0.99-1.11) | 1.22 (1.14-1.31) | |
| No | 9,852 | 1.11 (1.03-1.20) | 1.05 (0.99-1.11) | 1.00 | 1.04 (0.99-1.1) | 1.19 (1.11-1.28) | |
| Smoking status | 0.48 | ||||||
| Nonsmokers | 6,556 | 1.14 (1.04-1.24) | 1.01 (0.95-1.08) | 1.00 | 1.03 (0.96-1.10) | 1.19 (1.09-1.30) | |
| Former smokers | 7,900 | 1.19 (1.10-1.30) | 1.09 (1.03-1.16) | 1.00 | 1.10 (1.03-1.17) | 1.23 (1.14-1.33) | |
| Current smokers | 4,879 | 1.07 (0.96-1.19) | 1.02 (0.95-1.11) | 1.00 | 0.99 (0.92-1.07) | 1.19 (1.08-1.31) | |
| Body mass index, kg/m2 | 0.03 | ||||||
| Non-obese (<25.0) | 9,057 | 1.13 (1.04-1.22) | 1.02 (0.96-1.08) | 1.00 | 1.05 (0.99-1.11) | 1.24 (1.15-1.33) | |
| Overweight (25.0-29.9) | 6,753 | 1.13 (1.03-1.23) | 1.05 (0.98-1.12) | 1.00 | 1.07 (1.00-1.14) | 1.25 (1.15-1.35) | |
| Obese (≥30.0) | 3,525 | 1.19 (1.06-1.33) | 1.12 (1.02-1.23) | 1.00 | 1.00 (0.91-1.10) | 1.08 (0.96-1.21) | |
| Physical activity, METs/weekb | 0.09 | ||||||
| <15.4 (men), <10.0 (women) | 6,162 | 1.17 (1.07-1.28) | 1.12 (1.04-1.21) | 1.00 | 1.13 (1.06-1.21) | 1.28 (1.18-1.40) | |
| 15.4-33.3 (men), 10.0-20.7 (women) | 4,199 | 1.15 (1.03-1.28) | 1.05 (0.96-1.14) | 1.00 | 0.98 (0.91-1.07) | 1.13 (1.01-1.26) | |
| 33.4-63.9 (men), 20.8-45.9 (women) | 5,259 | 1.06 (0.96-1.18) | 1.00 (0.93-1.08) | 1.00 | 1.01 (0.93-1.08) | 1.19 (1.08-1.31) | |
| ≥64.0 (men), ≥46.0 (women) | 3,715 | 1.22 (1.08-1.38) | 1.00 (0.91-1.09) | 1.00 | 1.05 (0.96-1.14) | 1.20 (1.07-1.34) | |
| Sitting watching television, h/day | 0.10 | ||||||
| < 1 | 2,073 | 1.17 (1.01-1.36) | 1.11 (0.98-1.26) | 1.00 | 1.13 (1.00-1.28) | 1.38 (1.18-1.62) | |
| 1-4 | 14,120 | 1.13 (1.06-1.20) | 1.06 (1.01-1.11) | 1.00 | 1.02 (0.98-1.07) | 1.19 (1.12-1.26) | |
| ≥5 | 2,766 | 1.20 (1.06-1.37) | 0.95 (0.85-1.07) | 1.00 | 1.09 (0.99-1.22) | 1.17 (1.04-1.32) | |
| Healthy populationc | 2,437 | 1.08 (0.93-1.25) | 1.09 (0.98-1.21) | 1.00 | 1.05 (0.94-1.17) | 1.32 (1.14-1.53) | - |
Abbreviation: CI, Confidence Intervals; HR, Hazard Ratio; METs, metabolic equivalent of task; Pint, P-value for interaction
Hazard ratios were calculated with age as the time metric, adjusted for variables not relevant to the stratified variables: 5-year age groups at cohort entry, sex, ethnicity, education, marital status, history of hypertension or diabetes at enrollment, alcohol consumption, energy intake, body mass index, physical activity (METs per week for moderate activity, vigorous work and strenuous sports), hours spent daily watching television, and smoking history by inclusion of the following variables: [smoking status, average number of cigarettes, average number of cigarettes squared, number of years smoked (time dependent), number of years since quitting (time dependent), and interactions between ethnicity and the smoking variables].
Calculated using the Wald statistic for cross-product terms.
Restricted to men and women who are nonsmokers, non-obese, and who don't have hypertension nor diabetes at baseline (n=68,243).