Impact of CPAP Therapy on Cognition and Fatigue in Patients with Moderate to Severe Sleep Apnea: A Longitudinal Observational Study

Continued solicitation of cognitive resources eventually leads to cognitive fatigue (CF), i.e., a decrease in cognitive efficiency that develops during sustained cognitive demands in conditions of constrained processing time, independently of sleepiness. The expression of CF and its impact on cognition are partly contingent upon prior sleep quality and its restorative effects. Sleep in obstructive sleep apnea (OSA) may be largely restored through the use of continuous positive airway pressure (CPAP) treatment, contributing to a gradual improvement in sleep quality. In this longitudinal observational study, we investigated immediate and longer-term behavioral effects of CPAP treatment on cognitive functioning, evaluating outcomes after the initiation of treatment, and at three and six months, in compliant CPAP-treated OSA patients. Results indicate that CPAP therapy significantly enhances subjective sleep quality and cognitive functions, including episodic memory, inhibition, sustained attention, working memory, and executive control. Noticeable performance improvements were observed in CF-inducing tasks, particularly after six months of CPAP use. Participants also reported substantial gains in quality of life, reduced daytime sleepiness, and improved mood. These results confirm that CPAP therapy not only alleviates immediate physiological disturbances associated with OSA, but also supports cognitive recovery and enhanced overall daily functioning.