Correlates of daytime sleepiness in patients with asthma

Patients with asthma often complain of daytime sleepiness, which is usually attributed to a direct effect of asthma on nocturnal sleep quality. We investigated this and other potential explanations for daytime sleepiness among asthmatics.

One hundred fifteen adult asthmatics were assessed for perceived daytime sleepiness (one question item), subjective sleepiness (Epworth Sleepiness Scale score, ESS), obstructive sleep apnea risk (Sleep Apnea scale score within Sleep Disorders Questionnaire, SA-SDQ), asthma severity step, relevant comorbid conditions, and current asthma medications.

Among all subjects, 55% perceived excessive daytime sleepiness and 47% had ESS>10. Most subjects reported snoring (n=99, or 86%) and many snored habitually (n=44, 38%). The ESS correlated with SA-SDQ (P<0.0001), male gender (P=0.01), and asthma severity step (P=0.04). In a multiple regression model, the ESS was independently associated with SA-SDQ (P=0.0003) and male gender (P=0.02), but not with asthma severity step (P=0.51). There were no correlations between ESS and age, body mass index (BMI), forced expiratory volume in one second as percent of predicted value (FEV(1)%), comorbidities, or medication used to treat asthma.

Sleepiness is common in asthmatics and may reflect occult obstructive sleep apnea more often than effects of asthma itself, other comorbid conditions, or asthma medications.