Patients with obstructive sleep apnea (OSA) may blame their daytime difficulties on simple sleepiness, but new research suggests that their brains may be to blame. Specifically, their cognitive challenges may be caused by structural deficits in gray matter, brought on by the intermittent oxygen deprivation that comes with OSA. The good news is that these deficits may be partially or fully reversible with early detection and treatment, according to Italian researchers.