If REM dreaming is your minds way to sort through the day's activities and store memories better, wouldn't lucid dreaming frequently screw with your memory? Kinda like smoking bud, because it affects REM sleep. I noticed the weeks when I smoke 2-3 times a day for 7 day my memory of the week is reduced noticeably, compared to 7 days sober, I kinda can't remember certain conversations and what not.