I woke at 4:15 am, and fell deep asleep at the first sounds of my alarm, three hours later.
Not the first time that the sound of the alarm works like a hypnotising device.
Did get up just in time to be able to race the kids fed and well out of the door for school at the right timing.
Oddly enough, I think I understand how this might work. You're lying in bed thinking, "Sooner or later the bloody alarm clock's going to go off in my ear. Soon. Any minute now. Any
second now." And by the time it finally
does go off in your ear, you have built yourself up to the point where you now heave a huge sigh of relief, say, "Whew, thank Unnamed Deity, now I can finally relax!" and you go straight back to sleep. Does this sound plausible?