Associations Between Sleep Duration and Lifestyle Risk Factors Among Adolescents: A Cross-Sectional Study

Design and Participants

This cross-sectional study used data from the 2015-2019 national Youth Risk Behavior Survey (YRBS) that was a school-based, self-administered national survey conducted biennial by Centers for Disease Control and Prevention (CDC). ⁶ The YRBS uses a three-stage cluster sampling design to generate a representative sample of US high school students grades 9 through 12 from both private and public schools. ⁶ We combined data from three survey cycles (2015, 2017, 2019), including 43 391 respondents aged 14-18 years old. After excluding those with missing data on the outcome variables, the final analytical sample includes 31 871 respondents.

Measures

Sleep duration was assessed in the YRBS questionnaire through the question “On an average school night, how many hours of sleep do you get?” Responses were categorized into 3 levels, including “less than 6 hours”, “6 to 7 hours” and “8 hours and more”. ⁷

For outcomes, students were asked how many days they were physically active for a total of at least 60 minutes per day for the past 7 days. A dichotomized variable was created to indicate physical inactivity if students did not choose “7 days” based on the Physical Activity Guidelines for Americans for adolescents. ⁸ Similarly, a dichotomized variable was created to indicate insufficient breakfast consumption if students did not choose “7 days”. ⁹ To assess current tobacco use, students were asked the number of days they smoked cigarettes, cigars, used smokeless tobacco or electronic vapor products during the past 30 days, respectively. Students who smoked any of those products on at least 1 day during the 30 days were classified as current tobacco user. ¹⁰ To assess current binge drinking, students were asked the number of days they have 4 (female) or 5 (male) more drinks of alcohol during the past 30 days. Students who have 4 (female) or 5 (male) more drinks of alcohol in a row on at least 1 day during the 30 days were classified as current binge drinker. ¹¹

Confounders of our study included age (14 years old, 15 years old, 16 years old, 17 years old, 18 years old or older), biological sex (male or female), race/ethnicity (non-Hispanic White, non-Hispanic Black, Hispanic/Latino, and other), academic grades (mostly A’s, mostly B’s, mostly C’s, and mostly D’or F’s), and body mass index (BMI) weight status categories (underweight, normal weight, overweight, and obese).

Analysis

We conducted descriptive analysis to examine the sample characteristics by sleep duration, using Rao-Scott chi-square test for categorical variables. Prevalence estimates and 95% confidence interval (CI) of sleep duration over time were also calculated. To examine the association between sleep duration and lifestyle risk factors, we conducted separate logistic regression analyses for each outcome, controlling for potential confounders. Adjusted odds ratios (aOR) and 95% CIs were reported. To explore the potential effect modification of biological sex, we added an interaction term between sleep duration and sex to each logistic regression model. Only results with a significant interaction term (P < .05) were reported for physical inactivity and tobacco use. Multiple imputation by chained equations (m = 15) was used to account for missing data. Weighted analyses were performed using survey analysis procedures in SAS version 9.4 (SAS institute INC., Cary, North Carolina) to account for the complex sampling design of the YRBS. An alpha of 0.05 was considered statistically significant.

Summary

Our study observed a decreasing prevalence of sleeping 8 hours and more from 2015 to 2019, but an increasing prevalence of sleeping less than 6 hours and 6 to 7 hours. We found dose-response associations between short sleep duration and elevated risks of the four lifestyle risk factors. Our findings were in line with previous studies suggesting the negative association between short sleep duration and physical activity. We also found that the relationship between short sleep duration and physical inactivity was more pronounced in boys than in girls. It is plausible that boys may need more time than girls to recover from insufficient sleep that limits their ability to engage in physical activity. ¹²

Emerging evidence suggests that individuals with short sleep duration tend to have more late-time eating and snacks consumption. ¹³ Therefore, adolescents with such irregular eating time would not feel hungry in the morning and be more likely to skip breakfast.

Our study findings support previous studies illustrating that insufficient sleep was associated with increased risk of smoking and alcohol drinking. ¹⁴ We also observed a more pronounced association between short sleep duration and tobacco use in girls than in boys. As females are more likely to suffer from poor mental health than males. ¹⁵ they may use more tobacco as a way of releasing stress.

Limitations

Firstly, the cross-sectional nature of the data prevented us from drawing conclusions about causal relationships. Secondly, data on sleep duration and lifestyle behaviors were self-reported, which may be subject to potential information bias. However, such information bias is also likely non-differential which may bias our points estimates toward the null value. Thirdly, residual confounding may still be present since data on some potential confounders such as urbanicity, parental education, and mental health was not available. Lastly, participants of the YRBS survey are only those who attend public and private schools, and therefore are not representative of all teenagers in this age group.

Significance

This study suggests that insufficient sleep is a common and significant issue among American adolescents and is associated with increased risks of multiple lifestyle risk factors. Our study also adds evidence of a potential stronger association between insufficient sleep and a specific unhealthy lifestyle behavior in boys or in girls. This highlights the need to develop and implement multilevel interventions to address sleep deprivation and promote good sleep hygiene among adolescents. Parents should be involved in sleep intervention efforts to learn how to improve sleep. School-based intervention is also important to educate students about healthy sleep habits, particularly for those with sleep and mental health problems.

So What? Implications for Health Promotion Practitioners and Researchers