Of the included 2495 participants, 34.39% were Non-Hispanic White, 27.37% were Hispanic, 20.96% were Non-Hispanic Black, 13.51% were Non-Hispanic Asian, and 3.77% were of ethnicities. The median age (Q1, Q3) was 44.00 (31.00–58.00) years old. As of marital status, 63.25% were married or living with a partner, 20.72% were never married, 11.26% were divorced or separated, and 4.77% were widowed. The highest proportion of the education level was college graduate or above (33.23%), followed by some college (31.10%), high school (19.40%), and less than high school (16.27%). PIR groups corresponded to 33.31, 33.19, and 33.51% of the population from the low PIR group to the high PIR group. Most participants did not report trouble in sleep (75.67%). A total of 751 (30.10%) participants were normal weight, 823 (33.00%) were classified as overweight, and 921 (36.91%) were obese. The average sleep duration of the overall population was 7.74 ± 1.24 h, with 64.73% of the study population slept at a normal duration.
The demographic characteristics of the overweight group and obese group were compared with the normal weight group to address potential covariates, as summarized in Table 1. Age (P < 0.001), sleep duration (P < 0.001), sex (P < 0.001), race (P < 0.001), marital status (P < 0.001), education level (P < 0.001), total number of people in the family (P = 0.003), number of children aged ≤5 years (P = 0.002), and daytime sleepiness (P = 0.016) were significantly different among the three weight groups. The median age of the overweight group was the highest across three weight groups (45.00 years [31.00–59.00 years]), followed by the obese group (44.00 years [32.00–58.00 years]) and the normal weight group (41.00 years [27.00–54.00 years]). The average sleep time of the three groups was 7.84 ± 1.15 h, 7.72 ± 1.38 h, and 7.57 ± 1.48 h of the normal weight, overweight, and obese groups, respectively. Baseline variables of the overweight and obese groups were compared with the normal weight group separately to determine the covariates of each weight group, which were not presented in tables. Comparing to the normal weight group, age, sex, race, marital status, and education level were significantly different in the overweight group, which were adjusted in the following overweight analyses. For the obese group, age, sex, race, marital status, education level, total number of family members, and number of children aged ≤5 years were difference from the normal weight group. Thus, these covariates were adjusted in the later obese analyses.
Sleep duration and obesity
The normal-sleep group was determined to be the reference group of all logistic regression analyses (Table 2). When comparing to the normal-sleep group, the short-sleep group indicated a significantly higher odds of overweight (OR = 1.752, 95%CI: 1.243–2.470, P = 0.003), while the overweight incidence of the long-sleep group was not statistically different from the reference (OR = 1.346, 95%CI: 0.826–2.193, P = 0.214). After adjusting for age, sex, race, marital status, and education level, the pattern remained consistent, illustrating a significantly higher odds of overweight in the short-sleep group (OR = 1.825, 95%CI: 1.251–2.661, P = 0.004). The occurrence of obesity was statistically higher in both the short-sleep (OR = 1.832, 95%CI: 1.215–2.762, P = 0.007) and the long-sleep group (OR = 1.370, 95%CI: 1.043–1.800, P = 0.027) as compared to the reference in the unadjusted model. The short-sleep group indicated a significantly higher odds of obesity (OR = 1.574, 95%CI: 1.201–2.064, P = 0.001) after controlling for age, sex, race, marital status, education level, total number of family members, and number of children aged ≤5 years, while no significant difference was observed in the long-sleep group.
Subgroup analyses further stratified the population by age and sex. When stratifying by age, 436 participants were classified as the older adult group, and 2059 participants were categorized as the adult group (Table 3). In the adult group, the overweight odds of the short-sleep group were significantly higher than that of the normal-sleep group (OR = 2.094, 95%CI: 1.444–3.038, P < 0.001), while the long-sleep group showed no statistical difference as compared to the reference (OR = 1.364, 95%CI: 0.875–2.126, P = 0.178). When controlling for sex, race, marital status, and education level, the results were allied with the unadjusted model, with the short-sleep group showing a significant increase in overweight incidence (OR = 1.951, 95%CI: 1.333–2.855, P = 0.002). A similar pattern was detected in the obese analysis, with the short-sleep group demonstrating a statistically higher occurrence of obesity in the unadjusted (OR = 1.773, 95%CI: 1.181–2.660, P = 0.009) and adjusted model (OR = 1.475, 95%CI: 1.085–2.006, P = 0.0013) controlling for age, sex, race, marital status, education level, total number of family members, and number of children aged ≤5 years, while no significance was discovered in the long-sleep group. In contrast, findings of the older adult group were divergent from the adult group, displaying no statistical differences in any of the comparisons among the older adults.
In the sex-stratified analyses (Table 4), there were 1244 males and 1251 females in the subgroup analysis. For females, the short-sleep group (OR = 2.491, 95%CI: 1.281–4.844, P = 0.01) illustrated an elevated odds of overweight than that of the normal-sleep group when adjusting for age, race, marital status, and education level in the female population. Conversely, the overweight incidence of the short-sleep group (OR = 1.504, 95%CI: 0.980–2.307, P = 0.06) was not statistically different from the odds ratio in the normal-sleep group in the male group. The long-sleep duration was not associated with overweight odds in both the female and male groups.
The obesity incidence was significantly higher in the short-sleep group (OR = 2.590, 95%CI: 1.441–4.656, P < 0.001), as well as the long-sleep group (OR = 1.698, 95%CI: 1.055–2.734, P = 0.029) when controlling for age, sex, race, marital status, education level, total number of family members, and number of children aged ≤5 years. Nevertheless, no association was detected in the short-sleep and long-sleep group of the male analysis.