Asthma happens. While daytime attacks are obvious, those that occur at night may be more subtle. Patients may notice that they have trouble falling or staying asleep or that they are sleepy during the day. Some patients, however, experience disturbing snoring, choking, coughing, and/or breathlessness during sleep.
Teodorescu and colleagues,1 have published numerous studies on sleep disorders in persons with asthma, finding it to be a common issue. These researchers are not alone: recent data from the Room to Breathe Survey (a global initiative underway in Canada, Greece, Hungary, The Netherlands, the United Kingdom, and South Africa) shows that 59% of 943 children and adolescents who had asthma and were interviewed reported nocturnal awakening.2
What mechanisms cause sleep disturbance in persons with asthma? In persons who do not have asthma, PEFR and FEV1 are greatest at night and lowest in the morning. In asthmatic persons, this pattern is similar but exaggerated. Flow rates are lower and there is more variation in respiratory function. The amount of nitric oxide exhaled in the morning is lower in persons who do have asthma than in those who do not. The net result of this is increased bronchoconstriction and airway resistance, occurring in airways that are already inflamed. Cortisol and corticotropin levels are peaking simultaneously—a response that is most pronounced in persons with nocturnal asthma (compared with both asthmatics and non-asthmatics).3
The other part of the equation is that REM sleep is heaviest during early morning. During REM periods, respiratory function is normally subdued (tidal volume and functional residual capacity both decline).4 For persons with asthma, this period then becomes a sort of “double whammy,” with compounded airflow restriction that can compromise the quality of sleep.
The consequences of lack of sleep are signficant—especially for children with asthma. Horner and colleagues,5 working at the Washington University School of Medicine in St Louis, Missouri, examined the clinical consequences of nocturnal asthma symptoms requiring albuterol (NASRAs) in children with mild-to-moderate persistent asthma. A total of 285 children aged 6 to 14 years were randomized to receive one of 3 controller regimens and completed daily symptom diaries for 48 weeks.5
Results showed that 72.2% of the children experienced at least one NASRA, and 24.3% had 13 or more episodes. Over 80% of nocturnal symptoms occurred when asthma was not exacerbated.5 Symptoms were associated with the following next-day events: albuterol use (56.9%), school absence (5.0%), and doctor contact (3.7%). Nocturnal symptoms clearly contributed to school absence, increased medication use, and physician contact, although they did not predict exacerbation of asthma.5
In another recent study, Fagnano and team6 studied the impact of nocturnal asthma on the quality of life (QOL) in a group of 287 urban children with persistent asthma who were enrolled in the School-Based Asthma Therapy trial of Rochester, New York. Caregivers reported on nocturnal asthma symptoms (number of nights/2 weeks with wheezing or coughing), parent QOL, and sleep quality by using the validated Children's Sleep Habits Questionnaire.6
Forty-one percent of the children had intermittent nocturnal asthma symptoms, which were mild and persistent in 23% and moderate to severe in 36%.6 Children's average total sleep quality score was 51 (range, 33-99, with a clincally significant cut-off score of 41), indicating pervasive sleep disturbances. Sleep scores were worse in the children having the worst nocturnal asthma symptoms. Not only were the children affected, but their parents were troubled as well: parental QOL scores decreased with the severity of their child’s illness.6
Answers to questions about sleep quality and daytime sleepiness are important, during an initial history and on an ongoing basis. Answers may offer clues regarding inital asthma severity and disease progression, and direct modification of the treatment plan. Controlling noctural asthma is certainly a worthy goal that could have significant impact on overall health, functional ability, and QOL--for adults, children, and their parents.