Do nocturnal asthma attacks influence sleep parameters and inflammatory markers? A cross-sectional population-based study

Purpose To evaluate the effects of nocturnal asthma on sleep parameters and inflammatory markers according to the severity of the condition in participants in the São Paulo Epidemiologic Sleep Study (EPISONO). Methods Data from the 2007 and 2018 editions of the EPISONO study were utilized. Subjects completed validated sleep and respiratory questionnaires, underwent nocturnal polysomnography and spirometry tests, and provided blood samples for the assessment of inflammatory parameters. Results Of 72 participants (67% women), 53% ( n = 38) had intermittent nocturnal asthma symptoms and 47% ( n = 34) had persistent asthma (mild, moderate, and severe). Individuals with persistent nocturnal symptoms had a higher body mass index (BMI), were more likely to have respiratory symptoms, and had worse lung function, a higher apnea-hypopnea index (AHI), and higher desaturation index than individuals with intermittent nocturnal symptoms. Positive associations were identified between nocturnal asthma and obstructive sleep apnea (OSA). A higher frequency of OSA was observed in participants with persistent asthma and participants with OSA were more likely to have persistent than intermittent asthma. However, there were no significant differences between the immunological parameters of those with intermittent or persistent asthma. Conclusions This study highlights the relevance of nocturnal symptoms as a valuable indicator of asthma severity. The findings also add to the existing body of evidence linking nocturnal asthma and OSA.