... since it was a loooong time ago, I was very little (well, littler than I am now, not-quite-5'2 isn't exactly towering over anyone, maybe 'very young' would be more correct) and I can't really remember the details very well - or I can, but I think they might be a little cloudy from retelling it to loads of people during sleepovers etc. I only thought of it just now because I happened to see a book just like the one I was reading at the time in the second-hand bookshop in town.
Anyway, enough babbling and apologising for not having the details very well... on with the story.
I remember it was night-time, after me and my brothers had been put to bed but before my parents had gone upstairs, so I was awake and reading - I always used to read until one of my parents came in and made me stop! The book I was reading was an Enid Blyton 'Famous Five' (see, told you I was very young :) one that was sort of like a choose-your-own-adventure book, and a game as well - it came in a clear plastic packet with a dice, a pretend torch, a map, some 'food cards' and the like. I was sitting cross-legged on my bed so that I could spread all the stuff out on the covers, and I happened to be facing in the direction of the door. I was doing quite well with the game and was very engrossed in it when I suddenly thought that perhaps I should look up (that still happens now, usually when one of my gerbils is escaping or something) and I did. My door was wide open - I would never let my parents shut it at night - and my bed was along the wall that the door was in, so that I couldn't see behind the door. But what I am still adamant I did see was a pair of hands reaching from behind it, sort of flexing and grasping handfuls of air, then retreating.
I sat there for a few seconds in complete shock, and then a part of my brain said Go on, be scared (I remember that clearly) and I went hot then cold all over, and after about ten minutes I decided that my parents would know what to do and I jumped out of bed and ran downstairs. They calmed me down and said it was most likely just my little brother sleepwalking. I'm prepared to accept that that's possible, but I'd only ever known him sleepwalk once before, and to get to my room he'd have had to cross the landing, and the floorboards were so creaky I'm sure I'd've heard him. Also, although it's difficult to tell, I'm sure those hands were much too big to be my brother's, they were more like adult size.