Sleeeeeeep

I'm really bad at going to bed at a sensible time. I tell myself that I need to be in bed by 11.30, and with the lights out and trying to sleep by midnight, but as that time rolls around there's always an urgent need to play just one more level of my game, or read just one more chapter of my book. Last night was particularly bad, and I didn't make it to bed until nearly five, which when I'm getting up at sevenish is not something my body can cope with now I'm no longer quite so young as I once was. Usually it's better than that, but one-thirty or two is not uncommon, and I'm starting to resent being tired all the time.

Anyone else struggle with this, and if so, any suggestions more useful than "apply more willpower"?