Table 1.
Characteristics and lifestyle traits of participants according to sleep duration and bedtime.
| Variables | All | Sleep Duration |
P value* | Bedtimeb |
P value* | ||
|---|---|---|---|---|---|---|---|
| Non-Short Sleepers (n=581) | Short Sleepers (n=174) | Early Sleepers (n=380) | Late Sleepers (n=375) | ||||
| Total,% | 100 | 76.9 | 23.1 | 50.3 | 49.7 | ||
| Gender,%female | 73.5 | 75.0 | 68.4 | 0.08 | 78.2 | 68.8 | 0.004 |
| Age,y | 33.4±11.1 | 33.1±11.0 | 34.4±11.3 | 0.18 | 35.3±11.2 | 31.5±10.7 | <0.001 |
| Educationlevel | |||||||
| Less than High School,% | 1.5 | 0.9 | 3.5 | 0.04 | 1.3 | 1.6 | 0.01 |
| High school,% | 27.9 | 27.7 | 28.7 | 23.2 | 32.8 | ||
| College graduate or above,% | 70.6 | 71.4 | 67.8 | 75.5 | 65.6 | ||
| Brazilmacro-region | |||||||
| North,% | 3.3 | 2.9 | 4.6 | 0.13 | 2.4 | 4,3 | 0.18 |
| North East,% | 68.3 | 66.6 | 74.1 | 70.5 | 66,1 | ||
| Southeast,% | 20.3 | 22.2 | 13.8 | 19.7 | 20,8 | ||
| South,% | 3.6 | 3.6 | 3.5 | 2.4 | 4,8 | ||
| Midwest,% | 4.5 | 4.7 | 4.0 | 5.0 | 4,0 | ||
| MaritalStatus | |||||||
| Married/Living with Partner,% | 38.5 | 39.9 | 33.9 | 0.15 | 47.1 | 29,9 | <0.001 |
| BMI,kg/m2 | 25.1±5.0 | 24.8±5.0 | 26.0±5.1 | 0.006 | 24.8±4.8 | 25.4±5.2 | 0.13 |
| Overweight(BMI≥25kg/m2),% | 44.8 | 42.7 | 51.7 | 0.03 | 44.5 | 45,1 | 0.87 |
| Dietquality | 35.7±4.3 | 35.8±4.2 | 35.4±4.5 | 0.23 | 36.1±4.3 | 35,3±4,2 | 0.01 |
| Low (1st tertile),% | 38.7 | 38.4 | 39.7 | 0.95 | 36.6 | 40,8 | 0,03 |
| Intermediate (2d tertile),% | 34.7 | 34.9 | 33.9 | 32.6 | 36,8 | ||
| Good (3rd tertile),% | 26.6 | 26.7 | 26.4 | 30.8 | 22,4 | ||
| Sleeptraits | |||||||
| Sleep duration,h/night | 7.7±1.2 | 8.2±0.9 | 6.2±0.7 | <0.001 | 8.2±1.0 | 7.4±1.2 | <0.001 |
| Wake-up time,hh:mm | 07:06±1:24 | 07:18±1:24 | 06:18±1:30 | <0.001 | 06:30±1:06 | 07:42±1:30 | <0.001 |
| Bedtime,hh:mm | 23:18±1:24 | 23:06±1:18 | 00:06±1:36 | <0.001 | 22:18±0:42 | 00:18±1:12 | <0.001 |
| Nocturnal awakenings,n/night | 1.4±1.3 | 1.3±1.2 | 1.6±1.5 | 0.002 | 1.5±1.2 | 1.3±1.3 | 0.16 |
| Poor Sleep Quality,% | 33.1 | 28.2 | 49.4 | <0.001 | 27.6 | 38.7 | 0.001 |
| Chronotype,% | |||||||
| Morning | 62.9 | 63.0 | 62.6 | 0.49 | 89.2 | 36,3 | <0.001 |
| Indifferent | 21.2 | 21.9 | 19.0 | 9.2 | 33.3 | ||
| Evening | 15.9 | 15.1 | 18.4 | 1.6 | 30,4 | ||
| Lifestyletraits | |||||||
| Physical Activity,% yes | 65.2 | 66.4 | 60.9 | 0.18 | 67.1 | 63,2 | 0.26 |
| Physical activity,m/week | 155.4±176.0 | 151.0±165.3 | 169.9±207.3 | 0.21 | 163.1±190.6 | 147,6±159,6 | 0.22 |
| < 150 m/week,% | 56.4 | 58.0 | 51.1 | 0.11 | 57.9 | 54.8 | 0.38 |
| Screen Time,m/day | 219.9±167.2 | 217.7±164.0 | 227.2±177.8 | 0.51 | 192.5±144.6 | 247,8±183.4 | <0.001 |
| Screen Time before bed,m | 68.6±87.3 | 62.0±72.7 | 90.8±121.8 | <0.001 | 58.3±73.4 | 79,1±98,4 | 0.001 |
| Smokers,% | 3.6 | 3.1 | 5.2 | 0.19 | 2.1 | 5.1 | 0.03 |
| Alcohol use,% | 49.8 | 50.3 | 48.3 | 0.64 | 46.8 | 52,8 | 0.10 |
Abbreviations: BMI body mass index.
Values are shown as means ± SDs or percentages.
a Sleep duration groups were defined as follows: non-short-sleepers≥7 h/night, short-sleepers<7 h/night [ [29]].
*P values are derived from the student's t-test (for continuous variables) and the chi-square test (for categorical variables). Significant P-values ≤0.05 are shown in bold.
b
Bedtime groups were defined, depending on the median population as follows: early-sleepers≤23:08, late-sleepers>23:08.