Sleep duration, asthma and obesity.

BACKGROUND

Obesity is more prevalent in asthmatics. Sleep duration is a novel risk factor for obesity in general populations.

OBJECTIVE

We tested the association of sleep duration and asthma characteristics with obesity.

METHODS

Adults at tertiary clinics were surveyed on asthma symptoms and habitual sleep duration. Medical records were used to assess asthma severity step (1-4), extract height and weight, current medications and diagnosed comorbid conditions. BMI ≥30 kg/m(2) defined obesity. Habitual sleep was categorized as <6 (very short), 6 to <7 h (short), 7-8 h (normal), >8 to ≤9 h (long) and >9 h (very long). Inhaled corticosteroid doses were categorized as low, moderate and high.

RESULTS

Among 611 participants (mean BMI 30 ± 8), 249 (41%) were obese. After adjustment for covariates, obesity was associated with short and very long sleep: as compared to normal sleepers, the odds of being obese were on an average 66% higher ([95% CI: 1.07-2.57], p = 0.02) among short and 124% higher ([1.08-1.65], p = 0.03) among very long sleepers, and the association with very short sleep approached significance (1.74 [0.96-3.14], p = 0.06). Obesity was also significantly related to highest asthma step (1.87 [1.09-3.21], p = 0.02) and psychopathology (1.64 [1.08-2.48], p = 0.02), and a trend was seen with high-dose inhaled corticosteroids (1.82 [0.93-3.56], p = 0.08).

CONCLUSIONS

Obesity in asthmatics is associated with shorter and very long sleep duration, worse asthma severity, psychopathology and high-dose inhaled corticosteroids. Although this cross-sectional study cannot prove causality, we speculate that further investigation of sleep may provide new opportunities to reduce the rising prevalence of obesity among asthmatics.