Sleep Disorders Are Distinctively Associated with Exercise Intolerance and Sedentary Behavior in Children with Cystic Fibrosis

Objective: To evaluate the presence of sleep disorders and its associations with exercise capacity and daily physical activity levels among children and adolescents with CF.

Methods: Children age 6-18 years with a diagnosis of CF were recruited. Information regarding sociodemographic profile, pulmonary function and nutritional status were collected. Sleep disorders (polysomnography), exercise capacity (modified shuttle test - MST) and daily physical activity levels (questionnaire and five days accelerometer use) were evaluated.

Results: Thirty-one patients, median age of 9.6 years and forced expiratory volume in 1 s (FEV) of 68.1 ± 24.4%, were included. Obstructive sleep apnea syndrome (OSAS) was present in 32.3% and nocturnal hypoxemia in 29%. The MST distance correlated with the mean peripheral oxyhemoglobin saturation (SpO) during sleep (r = 0.40) and the percent of total sleep time with SpO<90% (r = -0.49). The final MST SpO correlated with the occurrence of OSAS (r = -0.48) and mean nocturnal SpO (r = 0.45). Sedentary activities, as measured by accelerometry, correlated with sleep architecture, including the percent of stage II (r = 0.60) and rapid eye movement (REM) stage sleep (r = -0.37). Patients with OSAS and nocturnal hypoxemia presented lower values (p < 0.05) of distance and final SpO in the MST. Nocturnal hypoxemia was the main variable to influence exercise capacity (r = 0.521).

Conclusion: Sleep disorders are distinctively related with exercise capacity and daily physical activity levels, as nocturnal hypoxemia is associated with exercise intolerance and sleep architecture disorders are associated with sedentary physical activity levels.