Significance of Sleep-disordered breathing in the CF population
Insufficient sleep, which can be a consequence of sleep-disordered breathing, has been recognized as a risk factor for mortality in young adults and is of high concern10. Sleep complaints occur in 40% of children with CF, with 70% reporting daytime sleepiness11.  It is important to note that neither malnutrition nor respiratory muscle weakness are necessary to develop hypoxemia or hypercapnia during sleep, putting a larger portion of the CF population at risk for sleep-disordered breathing than was originally believed 12. Obstructive sleep apnea in particular is noted to have a high prevalence in CF children, and OSA can lead to deteriorating school performance, failure to thrive, and worsening lung function13. Besides, sleep-disordered breathing in children with chronic pulmonary diseases including CF can lead to neurocognitive effects that hamper development s14. Therefore, it is important that CF pediatric providers are aware of the impact of sleep-disordered breathing in their patients.
As the CF population overall has improved longevity, medical conditions that are associated with sleep-disordered breathing such as obesity, diabetes, and cardiovascular diseases are emerging.15-18 It is
important to acknowledge that the adult population with CF has exceeded the pediatric population since 2015, and increased age is known to be a major risk factors for the development of sleep-disordered breathing.19,20 Improvement in genetic diagnosis of CF has also led to milder phenotypes of CF being recognized in later life ,21 when patients are at risk for other age related comorbidities. Also, as this population gains weight, the risk for OSA in particular is increased. A study by Peppard et al. has shown that a 10% increase in weight increases the risk of OSA 6-fold.20 Cardiovascular complications
such as hypertension, coronary artery disease, and stroke have been described in adults with OSA22, 23,24. Autonomic dysfunction in OSA is associated with impaired glucose tolerance25, and the implications
of the development of diabetes is well known to CF clinicians. In addition, fragmented sleep caused by sleep-disordered breathing is known to cause fatigue, which is highly prevalent in CF and negatively associated with wellbeing and emotional health 26. The fragmented sleep that leads to fatigue is a result of frequent nocturnal awakenings. It has been shown that forced expiratory volume in 1 second (FEV1) inversely correlates with the number of nocturnal awakenings, which means there is more fragmented sleep as lung function declines.27
Without question, the above concerns highlight that CF clinicians need to be looking for and treating sleep-disordered breathing in these patients.