[mmaldacker]

Not a single data point in this theory. The reason you sometimes wake up just before the alarm (at least I wake up before my alarm because I actually check the time) is because of conditioning. Our biological clock is pretty accurate. An example of that, in university I could easily sleep on the week ends till noon. Now that i've been working for many years and waking up regularly at the same time during the week, I wake up naturally around the same time during the week end (unless I went out late the day before of course).