A study involving 135 adults (33-65) has found that, not only did patients with obstructive sleep apnea who were being treated with CPAP therapy outperform untreated OSA patients on an overnight picture memory task, but they outperformed controls who did not have OSA. The memory task involved being shown 20 photographs before spending the night in the sleep lab, and then having to choose the familiar photo from 20 similar pairs in the morning. CPAP therapy provides a steady stream of air through a mask that is worn during sleep.
Reference:
Payne, J.D. et al. 2010. Regeneration of overnight memory consolidation ability in cpap patients. Presented at SLEEP 2010, the 24th annual meeting of the Associated Professional Sleep Societies LLC, in San Antonio, Texas.