Table 1.
Baseline characteristics of the HCHS/SOL Sueño Ancillary Study population, by sleep regularity index (SRI) in quartiles
| SRI | |||||||
|---|---|---|---|---|---|---|---|
| Overall | Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | P* | ||
| N | 2107 | 526 | 526 | 529 | 526 | ||
| Mean (SD) of SRI | 69.4 (10.8) | 54.8 (9.0) | 68.0 (2.2) | 74.2 (1.5) | 80.7 (2.8) | ||
| Range of SRI | 2.4 to 92.4 | 2.4 to 63.8 | 63.8 to 71.5 | 71.5 to 77.0 | 77.0 to 92.4 | ||
| Age, years | 40.7 (0.4) | 37.9 (0.8) | 39.8 (0.8) | 42.7 (0.8) | 44.0 (0.9) | <.001 | |
| Sex | Male | 749 (48.9%) | 58.4% | 48.3% | 44.2% | 40.8% | <.001 |
| Female | 1358 (51.1%) | 41.6% | 51.7% | 55.8% | 59.2% | ||
| Body mass index†, kg/m2 | 29.8 (0.2) | 29.5 (0.4) | 29.7 (0.4) | 30.1 (0.4) | 29.9 (0.4) | .777 | |
| Hispanic/Latino background | Central American | 287 (5.9%) | 5.3% | 5.6% | 6.7% | 6.2% | <.001 |
| Cuban | 379 (20.4%) | 18.2% | 22.1% | 19.9% | 22.0% | ||
| Dominican | 262 (12.9%) | 17.7% | 12.9% | 9.8% | 9.4% | ||
| Mexican | 563 (36.9%) | 29.0% | 33.4% | 44.3% | 44.5% | ||
| Puerto Rican | 442 (20.2%) | 26.8% | 22.2% | 15.7% | 13.1% | ||
| South American | 174 (3.7%) | 2.9% | 3.8% | 3.7% | 4.8% | ||
| Study site | Bronx | 532 (29.7%) | 40.2% | 32.1% | 23.0% | 18.7% | <.001 |
| Chicago | 575 (16.5%) | 16.3% | 15.1% | 14.5% | 20.8% | ||
| Miami | 653 (27.9%) | 24.7% | 29.4% | 28.3% | 30.2% | ||
| San Diego | 347 (26.0%) | 18.8% | 23.5% | 34.3% | 30.3% | ||
| Nativity | Lived in United States <10 years | 540 (28.1%) | 22.5% | 33.4% | 29.7% | 28.0% | <.001 |
| Lived 10 to 20 years in United States | 492 (22.1%) | 16.9% | 19.9% | 28.5% | 25.2% | ||
| Lived in United States ≥20 years, but not US born | 724 (25.1%) | 24.6% | 23.3% | 24.5% | 28.6% | ||
| US-born | 344 (24.7%) | 36.0% | 23.3% | 17.3% | 18.3% | ||
| Educational level† | No high school diploma | 672 (29.4%) | 33.0% | 24.2% | 29.5% | 30.8% | .040 |
| At most a high school diploma | 551 (30.0%) | 31.8% | 32.3% | 24.3% | 30.8% | ||
| Greater than high school | 881 (40.6%) | 35.2% | 43.5% | 46.2% | 38.3% | ||
| Household income† | Less than $20 000 | 954 (47.5%) | 52.2% | 50.5% | 44.6% | 40.5% | .163 |
| $20 000 to $50 000 | 810 (41.9%) | 39.6% | 38.5% | 44.0% | 47.0% | ||
| More than $50 000 | 185 (10.6%) | 8.2% | 11.0% | 11.4% | 12.6% | ||
| Work schedule† | Non-working or retired | 876 (41.6%) | 49.0% | 43.0% | 35.7% | 35.6% | <.001 |
| Non-shift workers | 795 (35.7%) | 27.0% | 33.8% | 39.7% | 46.3% | ||
| Shift workers | 434 (22.7%) | 24.0% | 23.2% | 24.5% | 18.1% | ||
| Physical activity‡ | 221.1 (2.3) | 223.1 (4.5) | 218.3 (4.5) | 220.1 (4.2) | 222.7 (3.9) | .834 | |
| Average sleep duration, hours | 7.60 (0.04) | 7.58 (0.07) | 7.73 (0.08) | 7.59 (0.06) | 7.49 (0.05) | .107 | |
| Average sleep onset | 0:13 (0:04) | 0:50 (0:07) | 0:15 (0:07) | 23:51 (0:05) | 23:42 (0:07) | <.001 | |
| Average midsleep point | 4:05 (0:03) | 4:46 (0:07) | 4:11 (0:06) | 3:39 (0:04) | 3:27 (0:06) | <.001 | |
| SD of sleep duration, minutes | 85.01 (1.28) | 117.21 (2.71) | 83.63 (2.04) | 71.01 (1.92) | 55.10 (1.32) | <.001 | |
| SD of sleep onset, minutes | 68.61 (1.45) | 104.37 (3.37) | 64.62 (1.76) | 51.92 (1.22) | 39.93 (0.99) | <.001 | |
| Inter-daily stability†, % | 75.59 (0.50) | 61.90 (0.92) | 76.44 (0.64) | 81.96 (0.50) | 88.00 (0.27) | <.001 | |
| Sleep Medication use† | Less than once per week | 1805 (86.3%) | 84.2% | 83.4% | 88.5% | 90.5% | .176 |
| 1 to 4 times per week | 164 (7.1%) | 7.8% | 8.3% | 6.3% | 5.5% | ||
| More than 5 times per week | 135 (6.6%) | 8.0% | 8.3% | 5.2% | 4.0% | ||
| Apnea-hypopnea index†, events per hour | <15 | 1891 (92.6%) | 92.4% | 92.1% | 92.6% | 94.0% | .806 |
| ≥15 | 183 (7.4%) | 7.6% | 7.9% | 7.4% | 6.0% | ||
| Depressive symptoms†,§ | 7.2 (0.2) | 8.2 (0.4) | 7.2 (0.3) | 6.9 (0.4) | 6.1 (0.3) | <.001 |
Values are presented as mean (standard error) or absolute counts and percentages. Values (except absolute counts and summary statistics for SRI) are weighted for survey design and non-response and normalized to the age and sex distribution of the 2010 US Census. Significant p-values are marked in bold. Quartile 1—least regular SRI, Quartile 4—most regular SRI.
*Satterthwaite adjusted Wald tests for continuous variables, and Rao-Scott second-order correction Chi-Square tests for categorical variables.
†Number of missing values: 22 for body mass index, 3 for educational level, 158 for household income, 2 for work schedule, 363 for inter-daily stability, 3 for sleep medication use, 33 for apnea-hypopnea index, and 1 for depressive symptoms; the other variables are complete.
‡Physical activity given as the average activity counts per minute in 24-hour periods over all days from actigraphy.
§Depressive symptoms measured via the 10-item version of the Center for Epidemiological Studies Depression (CES-D10) questionnaire (scale: 0–30).