The relationship between sleep disturbance and pulmonary function in stable pediatric cystic fibrosis patients.

BACKGROUND Cystic fibrosis (CF) is the most common inherited disease affecting northern European populations. It is characterized by a progressive clinical course that causes diurnal and nocturnal pulmonary and gastrointestinal symptoms. OBJECTIVES To determine whether clinically stable pediatric patients with CF have lower sleep efficiency than healthy control subjects, and to examine the relationship between sleep efficiency and pulmonary function. METHODS Forty-four CF patients and 40 control subjects completed 5 days of actigraphy recordings. Additionally, sleep questionnaires were independently completed by all study participants and their parents. Pulmonary function testing was performed in all patients with CF. Multiple regression analysis was used to measure the independent correlation between sleep variables and pulmonary function. RESULTS CF patients had significantly lower sleep efficiency than control subjects. The FEV1 of these patients correlated positively with sleep duration and efficiency, and negatively with the number and duration of nocturnal awakenings, age, and body mass index (BMI). The independent effect of FEV1 on sleep was first examined. Age and FEV1 were the only variables that predicted sleep duration (R2 = 0.3; p = 0.0007), while FEV1 was the only variable predicting sleep efficiency (R2 = 0.28; p = 0.0002). When the independent effect of sleep on FEV1 was analyzed, sleep efficiency, BMI percentile, and gender predicted FEV1 (R2 = 0.46; p < or = 0.0001). The frequency of nocturnal cough reported by patients and their parents was an independent predictor of FEV1. CONCLUSIONS Pediatric patients with CF and stable pulmonary function have lower sleep efficiency and more frequent nocturnal awakenings than do healthy control subjects. After adjustment for demographic characteristics, there was an independent and significant correlation between sleep parameters and FEV1, when either sleep variables or FEV1 were used as dependent variables. These findings suggest a bidirectional relationship between sleep disturbance and CF lung disease.