Response Rates and Missing Values
Of the 355,710 individuals who participated in the BRFSS, a total of 188,765 people were asked the SC question (52.32% of the total BRFSS sample). Of those, 98.59% of respondents completed the item, with n=430 or 0.23% refusing to answer the question and n=2,228 or 1.18% responding with “don’t know.” Of those remaining, 159,856 (85.89%) provided complete data. This suggests that it is likely that the present data accurately represent the sample selected for study. The following regions were represented: Alabama, Alaska, Arkansas, California, Delaware, Washington DC, Florida, Georgia, Hawaii, Indiana, Iowa, Louisiana, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Mexico, North Dakota, Oklahoma, Oregon, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, West Virginia, Wisconsin, Wyoming, Puerto Rico, and the Virgin Islands.
Characteristics of subjects who responded to the SC question are reported in . This table shows that the variable with the highest rate of nonresponse was income. While this represents a small portion of the overall sample, it should be noted that analysis of individuals who did not report income showed that they were more likely to be in the youngest age and lowest education groups.
Characteristics of Respondents to the SC Question
Sleep Complaints or Insomnia
The SC item can be endorsed by individuals who sleep either too much or too little and thus may be endorsed by individuals with heterogeneous complaints. In order to better understand the meaning of this item (e.g., How much of the variance explained by this item reflects insomnia or sleep insufficiency?), responses to the SC question were compared to responses to a similar item asked of a subset of respondents (n=14,238) regarding sleep insufficiency (SI; “During the past 30 days, for about how many days have you felt you did not get enough rest or sleep?”). Both SC (range=0-14) and SI (range=0-30) were analyzed as continuous variables for this comparison, and SC values were only included from individuals who also reported SI. A Pearson correlation demonstrated that these two items are associated with each other to a significant degree (r=.47, p<.0001) but are not collinear (r2=.22) and thus not likely to reflect the same construct.
Categorical Variables Examined Alone and Adjusting for Covariates
displays the percentage of respondents indicating SC across race/ethnicity, education level, marital status, employment status and income level. displays the unadjusted OR, 95% CI and p values for all levels of these factors. A multivariate model adjusting for all covariates, including race/ethnicity, education level, marital status, employment status and income evaluated SC among groups was then conducted; displays the adjusted values.
Unadjusted Odds Ratios (OR) and 95% Confidence Intervals (CI) for reports of SC in Women and Men for Ethnicity, Education, Marital Status, Employment Status, and Income
Adjusted Odds Ratios (OR) and 95% Confidence Intervals (CI) for reports of SC in Women and Men for Race/Ethnicity, Education, Marital Status, Employment Status, and Income
Sleep Complaints and Ethnicity
In unadjusted analyses (), the Multiracial group was the only racial/ethnic group to report more SC than the reference category of White for both men and women. For females, the only other significant difference as a function of race/ethnicity was that the Hispanic group reported less SC than Whites. For males, both Asian and Hispanic groups reported less SC than White males. Once adjusted for other covariates ( and ), Black women now had less SC than White women. Hispanic women continued to have less SC than White women. For men, the only significant difference that remained was the reduced OR for SC in Asian/Other men; Multiracial males no longer had more SC than White males and Hispanic males no longer had less SC than White males, suggesting that for these groups, other socio-economic factors explained the different rates of SC in those race/ethnic groups relative to White males.
Figure 1 Odds Ratios (ORs) of SC for Men and Women, Across Race/Ethnicity (Reference Group = White). Among women, Asian/Other respondents reported the least SC, followed by Black/African-American and Latina respondents. These groups significantly differed from (more ...)
Sleep Complaints and Education
There was an inverse relationship between SC and education level, with the lowest education level predicting the highest SC in both gender groups (). In the adjusted model ( and ), using college graduates as the reference group, this pattern was maintained for both men and women, such that all groups reported more SC than the reference group, and reports of SC decreased as higher levels of educational attainment are reported. For women, a significant interaction was found, in that this relationship depended on race/ethnicity (described below).
Odds Ratios (ORs) of SC for Men and Women, Across Education Level (Reference Group = College Graduate). For both men and women, all groups reported more SC than college graduates.
Sleep Complaints and Marital Status
A significant association was observed between SC and marital status such that the highest likelihood of reporting SC occurred in all non-married groups of men and women in unadjusted analyses (). For both men and women, the highest ORs for SC were for those who were divorced and never married. In adjusted analyses ( and ), these differences were markedly attenuated but persisted in all cases except for those of widowed status.
Figure 3 Odds Ratios (ORs) of SC for Men and Women, Across Marital Status (Reference Group = Married). Except for widowed respondents, all groups reported significantly more SC than married respondents. The highest rates were for those never married or part of (more ...)
Sleep Complaints and Employment Status
In unadjusted analyses (), men and women in all non-employed categories had higher odds for SC compared to employed with the highest likelihood observed for both genders in the following categories: unable to work (approximately 3-7-fold), unemployed <1 year (approximately 2-fold), and unemployed >1 year (approximately 2-3-fold). In women, adjusted analysis ( and ) attenuated these associations for SC but the OR remained significant in all non-employed categories but the student group. Interestingly, in men, very different findings were observed in adjusted analysis: the likelihood for SC increased in five categories (self-employed, unemployed <1 year, unemployed >1 year, homemaker, and retired) compared to the referent group. The most prominent increase was for male homemakers, who had an OR of 3.44 (1.37 – 8.65, p=0.009) relative to the reference category of employed males; the comparable OR in females was 1.18 (1.05-1.33, p=0.007). Unemployed status greater than 1 year was associated with increased odds ratio for SC in both genders than unemployed less than 1 year, and this finding persisted in multivariable analysis. Overall, when compared to the respective referent group, men in non-employed categories had higher adjusted odds for SC than females.
Figure 4 Odds Ratios (ORs) of SC for Men and Women, Across Employment Status (Reference Group = Employed).For both men and women, unemployment was associated with increased SC. Employment conveyed slight benefit over self-employment and retirement in men, but (more ...)
Sleep Complaints and Income
Almost all categories of income for men and women had significantly increased OR for SC compared to the reference category (income greater than $75,000; ). For men and women, an inverse linear relationship was observed between income and SC, with progressively higher OR for SC as income category decreased. In the adjusted analysis ( and ), virtually all income categories had increased odds for SC, but the OR did not increase as prominently with declining income as in unadjusted analysis. Indeed, the lowest income group was no longer the highest risk group for SC after adjustment.
Figure 5 Odds Ratios (ORs) of SC for Men and Women, Across Income (Reference Group = >$75,000). Decreasing income was associates with increased rates of SC in men and women. However, there were no significant differences among men earning $25,000 or more. (more ...)
Interactions Among Covariates
When interactions among race/ethnicity and other covariates were explored from the adjusted model, some interesting patterns emerged (). In this analysis, white married males were used as the reference category. For marital status, Black/African American men were protected from SC if they were part of an unmarried couple. Hispanic/Latino men were more sensitive to being divorced or widowed. Also, Asian/Other men were more prone than White married men to SC if the Asian/Other men were widowed, separated or never married. Most notably, they experienced over a 10-fold increase in risk if they were separated. Special sensitivity to being separated was also evidenced in Multiracial men, who experienced a nearly 7.5-fold increase in likelihood of reporting SC, reflecting a significant difference from White married men.
Adjusted Odds Ratios (OR) and 95% Confidence Intervals (CI) of SC for Significant Interactions between Ethnicity and Education for Women and Marital Status, Employment Status, and Income for Men*
Regarding employment status, only Black/African American men had an association between SC and employment. They were much less likely to report SC (compared to White employed males) if they were a homemaker. This is in contrast to the male group as a whole, which had a much greater risk of reporting SC as a homemaker. They were also less likely to report SC if they were retired, and more likely to report SC if they were out of work for <1 year.
For income, Hispanic/Latino men were less likely to report SC (compared to $75,000+) if they reported income between $10,000-$15,000, $15,000-$20,000, $20,000-$25,000, and $35,000-$50,000, compared to White men in the highest income group. Compared to this group, Multiracial men were much more likely to report SC if they were in the lowest income group, and Asian/Other men were more likely to report SC if they reported income of $50,000-$75,000.
Education only demonstrated significant interaction terms for females. Asian/Other women demonstrated a 2-3-fold increased likelihood of reporting SC compared to college graduates, whether they did not complete high school, were a high school graduate, or had some college. All of these were significantly different from White women. Multiracial women who received some college reported less SC than college graduates, while all other groups reported more, and this OR was significantly different from that of White women. Hispanic/Latina women were less likely to report SC if they did not finish high school—a pattern not seen in any other group; this OR was also significantly different than that for White women.