I think you'll find a lot of females are not aware if they have nocturnal orgasms. As recently as 2005 a survey revealed that in excess of 25% of females were not aware of sleep related orgasms.
So, while you may be wanting anecodoal evidence of a females nocturnal bliss, finding that evidence, or more to the point, getting females to reveal what process occurred whilst they were sleeping to give them a warm, moist feeling inside their lady garden, could prove problematic.