I rarely sleep well if I know I have to get up at a certain time (say, if there's an alarm set). The slightest disturbance is magnified—a moment of wakefulness

I rarely sleep well if I know I have to get up at a certain time (say, if there's an alarm set). The slightest disturbance is magnified—a moment of wakefulness can turn in to half an hour, followed by another hour of half-sleep half-waking before I'm finally back under (maybe, if I'm lucky). Going to bed early just increases the chances that this will happen at 2AM and I'll be unable to go back to sleep at all, which is worse than waiting until I'm dead tired at 1AM and going to sleep then (and then still not getting enough, but at least it's usually solid). Then my weekend sleep-in day rolls along and I can stay under for 12 hours, falling right back into a deep sleep even if I've had to briefly get out of bed (bathroom), because I know I don't have to get up. Unfortunately, I have to have a day like this because my sleep is so bad during the week. I think it's related to anxiety about not getting enough sleep, which of course turns into an awful feedback loop. I've tried repeatedly to find info about this, as I am certain I'm not the only one by a long shot, but my Google-fu has failed me. Low levels of melatonin supplementation helps a bit, and at one point I was on Lunesta which got me through the night, but left me feeling only about as rested on ~8 hours as I did on ~6 hours of normal sleep, so I stopped. I can't even imagine how good my life would be without this problem, let alone if I had the kind of low sleep requirements that some do.