I was looking at how meditation affects the sleeping brain. The results were paradoxical, in that the more a person meditates, the better they report sleeping, but the worse they sleep on pretty much any objective measure of worse (as in, measured by polysomnography). I think this points to how meditation creates 24-hour vigilance and wakefulness, which in most people would be associated with poor sleep, but in meditators is associated with good sleep. I also ran a follow-up study using factor analysis to try to determine a way, combining objective and self-report data, that people might be ranked at various skills at meditation (e.g. relaxation, internal direction of attention, etc.). This did find two factors that clustered together, though more research is necessary to determine if these truly measure skill.