Just guessing, but I would assume it takes away from Deep sleep, depending on the amount. I really don't know how long I dream or the amount of deams but at times seems like too many. I've had sleep tests years ago, more for apnea, which is another issue but never looked at REM time. And CPAP was not for me. But dreams are recognizable people but I forget quickly, in whatever situation. Never scary. I've read quite a lot and all sorts of varying opinions. I was just wondering if I had less REM(if I truly am in that stage, that I am not getting enough quality sleep. That's all. Only wake up briefly once or a few times for whatever reason some nights. Thx for the reply