Table 2.
| Overall sample (n=1920) | Sleep duration <6 h/night (n=582) | Sleep duration ≥6 h/night (n=1338) | P value | |
|---|---|---|---|---|
| Demographic characteristics | ||||
| Age, y | 68.5 (9.1) | 68.5 (9.5) | 68.5 (9.0) | 0.990 |
| Female | 1038 (54) | 261 (45) | 777 (58) | <0.001 |
| White | 759 (40) | 147 (25) | 612 (46) | <0.001 |
| Black | 510 (27) | 221 (38) | 290 (21) | |
| Hispanic | 449 (23) | 146 (25) | 305 (23) | |
| Chinese‐American | 202 (10) | 70 (12) | 131 (10) | |
| Married | 1157 (61) | 313 (54) | 844 (64) | <0.001 |
| Have health insurance | 1824 (95) | 548 (94) | 1276 (95) | 0.300 |
| Education≥college | 1346 (70) | 402 (69) | 944 (71) | 0.500 |
| Born in the United States | 1298 (68) | 368 (63) | 930 (70) | 0.007 |
| Cardiometabolic risk factors | ||||
| BMI, kg/m2 | 28.8 (5.6) | 29.7 (5.8) | 28.5 (5.5) | <0.001 |
| BMI in overweight or obese categories | 1407 (73) | 463 (80) | 944 (71) | <0.001 |
| SBP, mm Hg | 122.5 (19.9) | 124.5 (21.5) | 121.6 (19.1) | 0.003 |
| DBP, mm Hg | 68.2 (9.9) | 69.9 (10.5) | 67.5 (9.6) | <0.001 |
| Hypertension | 1091 (57) | 359 (62) | 732 (55) | 0.005 |
| Fasting glucose, mg/dL | 101.5 (27.1) | 103.4 (27.8) | 100.7 (26.8) | 0.04 |
| Type 2 diabetes (treated or untreated) | 353 (18) | 120 (21) | 233 (17) | 0.020 |
| Total AHA LS7 score | 7.3 (2.5) | 7.0 (2.5) | 7.4 (2.5) | <0.001 |
| Sleep habits | ||||
| Sleep duration (h)‡ | 6.5 (1.3) | 4.9 (0.9) | 7.2 (0.8) | <0.001 |
| Poor sleep efficiency‡ , § | 186 (10) | 93 (16) | 93 (7) | <0.001 |
| Sleep efficiency, %‡ , § | 89.8 (3.7) | 88.5 (4.3) | 90.4 (3.3) | <0.001 |
| SD of sleep duration, min‡ | 84.0 (48) | 102.2 (43) | 76.1 (48) | <0.001 |
| High night‐to‐night variability in sleep duration (SD of sleep duration ≥90 vs <90 min)‡ | 38.6 (741) | 57.7 (336) | 30.3 (405) | <0.001 |
| SD of sleep onset timing, min‡ | 81.7 (97) | 112.3 (109) | 68.4 (64) | <0.001 |
| High night‐to‐night variability in sleep onset timing (SD of sleep onset timing ≥90 vs <90 min)‡ | 24.9 (479) | 45.0 (262) | 16.2 (217) | <0.001 |
| Insomnia‖ | 679 (36) | 215 (38) | 464 (35) | 0.360 |
| Excessive daytime sleepiness¶ | 270 (14) | 112 (20) | 158 (12) | <0.001 |
| Moderate to severe obstructive sleep apnea# | 812 (47) | 277 (54) | 535 (45) | 0.001 |
| Cardiovascular health metrics | ||||
| Total AHA LS7 score categories | ||||
| Poor | 984 (51) | 332 (57) | 652 (49) | 0.003 |
| Intermediate | 842 (44) | 228 (39) | 614 (46) | |
| Ideal | 94 (5) | 22 (4) | 72 (5) | |
| Diet score | ||||
| Poor | 809 (42) | 266 (46) | 543 (41) | 0.040 |
| Intermediate | 1027 (54) | 286 (49) | 741 (55) | |
| Ideal | 84 (4) | 30 (5) | 54 (4) | |
| Physical activity score | ||||
| Poor | 427 (22) | 140 (24) | 287 (22) | 0.440 |
| Intermediate | 281 (15) | 82 (14) | 199 (15) | |
| Ideal | 1212 (63) | 360 (62) | 852 (64) | |
| Smoking score | ||||
| Poor | 138 (7) | 58 (10) | 80 (6) | 0.007 |
| Intermediate | 899 (47) | 270 (46) | 629 (47) | |
| Ideal | 883 (46) | 254 (44) | 629 (47) | |
| Cholesterol score | ||||
| Poor | 828 (43) | 601 (39) | 601 (45) | 0.008 |
| Intermediate | 395 (21) | 281 (20) | 281 (21) | |
| Ideal | 697 (36) | 456 (41) | 456 (34) | |
| BMI score | ||||
| Poor | 695 (36) | 245 (42) | 450 (34) | <0.001 |
| Intermediate | 712 (37) | 218 (37) | 494 (37) | |
| Ideal | 513 (27) | 119 (21) | 394 (29) | |
| Blood pressure score | ||||
| Poor | 1288 (67) | 424 (73) | 864 (65) | 0.002 |
| Intermediate | 118 (6) | 87 (5) | 87 (7) | |
| Ideal | 514 (27) | 387 (22) | 387 (29) | |
| Glucose score | ||||
| Poor | 332 (17) | 115 (20) | 217 (16) | 0.012 |
| Intermediate | 416 (22) | 141 (24) | 275 (21) | |
| Ideal | 1172 (61) | 326 (56) | 846 (63) | |
AHA LS7 indicates American Heart Association Life's Simple 7; BMI, body mass index; BP, blood pressure; DBP, diastolic blood pressure; OSA, obstructive sleep apnea; PA, physical activity; and SBP, systolic blood pressure.
Continuous variables are shown as mean±SD, and categorical variables are shown as n (%).
T tests and chi‐square tests were used to examine differences in descriptive characteristics by sleep duration.
Sleep duration, sleep efficiency, and sleep variability were assessed from actigraphy measures performed using the Actiwatch Spectrum wrist actigraph (Philips Respironics, Murrysville, PA) worn on participants' nondominant wrists for 7 consecutive days.
Sleep efficiency was defined as the percentage of time in bed after lights off spent sleeping and was considered poor if <85%.
Insomnia was evaluated using the validated 5‐item Women's Health Initiative Insomnia Rating Scale (WHIIRS), which assesses insomnia symptoms including long sleep latency, sleep maintenance insomnia, early morning awakening, and poor sleep quality over the past 4 weeks. The score ranges from 0 to 4 for each item on the WHIIRS (0–20 total score range). Participants with WHIIRS scores ≥9 were considered to have insomnia.
The Epworth Sleepiness Scale (ESS) was used to measure daytime sleepiness. The total score of the ESS ranges from 0 to 24, and those with an ESS score >10 were considered to have excessive daytime sleepiness.
OSA was assessed using overnight polysomnography, which was conducted using a 15‐channel monitor (Compumedics Somte System; Compumedics Ltd., Abbotsville, Australia). An apnea‐hypopnea index (AHI) was calculated on the basis of the average number of all apneas plus hypopneas associated with a 4% desaturation per hour of sleep. Participants were considered to have moderate to severe OSA if they had an AHI ≥15 events/h.