Consider: you are willingly allowing control and consciousness to leave your body...or perhaps not willingly. After all, it WILL happen, regardless, so that's not exactly a willing situation. And this isn't some 'astral projection' or 'out-of-body experience', because you have no control and no memory of it.
On the one hand, you are tired and pass out. We've all had that time where you were reading or something, and so tired you were nodding off, only to snap your head back up at the 'last second'. But was it immediate? Did you lose 5 seconds or 5 minutes? And you were concentrating on something, weren't you, but you passed out anyway. And now you spend time trying to wake back up, knowing that it will happen again...it's like something is trying to knock you out and you are resisting.
On the other end of the spectrum, you go to bed, because it's that time, and maybe you know you have to get up early, and so you get comfy, turn off the lights, and lay there...staring at the ceiling. You're wired, not tired. You KNOW you need to sleep, but you can't, and you're loathe to get up and do something, because you know you'll either pass out doing it, or get into it and stay up until who-knows-when, and then you're screwed for tomorrow. So you lay there, waiting for sleep to hit you.
Now, to me, THAT is scary...because you don't feel tired, and yet, at some point, you will pass out. At least when you're nodding off, you feel tired, so you kinda expect things. But when you lay there, sleep sneaks up on you...one minute, you're still wide-awake, your mind running with whatever thoughts it's fixated on, quite aware of your surroundings, the next minute your alarm is going off, or the sun is up, or something that tells you that several hours have passed, at some point. Something has stolen several hours from your life, without you even noticing that it was coming.
You have to admit, it's a little disturbing. Yes, sleep is necessary; yes, it's a fact of life; no, I'm not afraid to go to sleep or anything like that. Just a slightly odd view on one of those things we ALL share. This all occured to me as I lay in bed last night, and I considered typing it up then, but I knew I had to get up early this morning.
Keep this in mind as you go to bed tonight, waiting for and dreading Monday morning.