I'm afraid I disagree with some of the advice in this thread. Going to bed and waking up at the same time every day without knowing what times to do so to suit your sleep cycle or trying to force yourself to sleep made matters worse for me.
As with others, it's only based on my personal experiences, but your descriptions sounds pretty similar to how I used to feel. Like you, I always struggled with getting up on time, no matter what time it was and what I tried, but when I was working freelance from home a year or so ago, I experimented with free running sleep.
You go to sleep when you're really tired, regardless of time, and get up when you're ready - no interruptions such as the alarm clock.
If you're the sort of person that doesn't get enough sleep and then crashes out and has a nap, it may come naturally, but it will seem odd to start with. After a while, you'll feel absolutely great when you wake up - you've had the sleep you needed - no more, no less.
You'll be able to work out just how long you'll sleep for, when you're likely to need more or less sleep, when you're likely to feel most tired. Try and make a note of rough times you went to sleep and woke up if it helps.
This might not be helpful unless you can get a couple of weeks off to give it a go, though to be honest, it took me a couple of months to adjust properly, but it's now allowed me to work out just how much sleep I need, and when I'm at my best.
I'm now on a much more organised schedule, but I still go to sleep whenever I feel tired, sometimes, I'll get four hours, sometimes ten, but I'm up at 3:15 every morning and feeling wide awake - I don't even need the alarm clock most mornings.
It's all very well people suggesting what works for them, be it a fixed bed time, six hours sleep, eight hours sleep, a nap in the afternoon, but try getting your body to tell you what it needs - it worked for me
