Introduction:
Sleep deprivation and large sleep variability are potential risk factors for obesity and cardiovascular diseases. While it is plausible that particulate air pollution may contribute to these unfavorable sleep patterns, very few studies have been conducted to assess the association between fine particulate (PM
2.5
) air pollution and objectively measured sleep duration and its variability in an adolescent U.S. population.
Hypothesis:
We tested the hypothesis that higher individual-level short-term PM
2.5
exposure is associated with shorter sleep duration and higher sleep variability among adolescents.
Methods:
We analyzed the available data collected from 421 adolescents who participated in the follow-up examination of the population-based Penn State Child Cohort (PSCC) study. To estimate individual-level short-term PM
2.5
exposure, a personal nephelometer (Thermo pDR-1200) was used to measure real-time PM
2.5
concentration for 24 hours from the study participants. The 24-hour mean PM
2.5
concentration was used to quantify the short-term PM
2.5
exposure. To obtain objectively-measured habitual sleep duration (HSD) and habitual sleep variability (HSV), an actigraphy (GT3X+) was used to collect sleep data for 7 consecutive nights, including 1 night in parallel with the PM
2.5
monitoring and 6 nights thereafter. HSD and HSV were calculated as the intra-individual mean and standard deviation (SD) of the 7-night sleep duration, respectively. Participants with < 5 nights (70% of 7 nights) of data were excluded from the analyses. The associations between the individual-level PM
2.5
exposure and HSD/HSV were evaluated by using multi-variable adjusted linear regression models, controlling for age, race, sex, BMI percentile, environmental temperature, and relative humidity.
Results:
The mean (SD) age of the study population was 16.9 (2.2) years. The study sample consisted of 54% males and 78% whites. The 24-hour mean (SD) of PM
2.5
concentration was 16.9 (26.8) μg/m
3
, while the average HSD and HSV were 7.0 (0.9) hours and 1.2 (0.6) hours, respectively. We observed that a 10 μg/m
3
increase in the 24-hour mean PM
2.5
was associated with significantly lower HSD [β (SE): -0.06 (0.03) hours, p=0.02] and larger HSV [β (SE): 0.04 (0.02) hours, p=0.04]. The effect sizes were approximately 7% of their respective SDs.
Conclusion:
Individual-level short-term PM
2.5
exposure is associated with objective-measured shorter sleep duration and higher night-to-night sleep variability among U.S. adolescents. These observed associations suggest that particulate air pollution exposure in early life may impact habitual sleep pattern, which may in turn be associated with the risks of obesity and cardiovascular diseases in later life.
Obesity and the cardiovascular health effects of fine particulate air pollution
