Do you drink alcohol in the evenings? Alcohol has a sedative effect at first, but your body compensates and so you'll tend to wake up when the alcohol wears off, rather than when you're fully rested.
Oh totally, 1 beer and my sleep goes from 5/10 to 2/10... I have 1 or 2 on weekends... but even then, that would at least make me sleep longer. But no, yesterday we had valentines dinner and I had two beers, and again today I woke up at 4h30...