Study objectives: This study aimed to assess the efficacy of a custom-made mandibular advancement splint for the treatment of obstructive sleep apnea with respect to neuropsychological functioning and mood state.

Methods: A randomized controlled crossover design was used in which 73 participants (mean age = 48.4, SD = 11.0, % men = 80.8) with at least 2 symptoms of obstructive sleep apnea and an apnea hypopnea index > or = 10 per hour underwent treatment with both mandibular advancement splint and an inactive oral device. Polysomnographic, neuropsychological and self-report measures were conducted at baseline and repeated after each of the two 4-week treatment phases.

Results: MAS treatment was associated with improvements on the somatic component of the Beck Depression Inventory and the Vigor-Activity and Fatigue-Inertia scales of the Profile of Mood States. While there were no improvements within the neuropsychological domains of attention/working memory, verbal memory, visuospatial or executive functioning, treatment with the mandibular advancement splint was associated with faster performance on a test of vigilance/psychomotor speed. These changes, however, did not correspond to the improved subjective sleepiness or apnea-hypopnea index during treatment.

Conclusions: Treatment with the mandibular advancement splint results in improvements in self-reported sleepiness, fatigue/energy levels and vigilance/psychomotor speed in patients with obstructive sleep apnea.