Why do I never have trouble sleeping?

Not as a result of trouble, ever.

About once every season I'll have a night of complete insomnia, where, for no reason, I'll stay up until between 3 and 4 AM. It has happened for years, but never seems related to anything in particular. It's never the result of caffeine, stress, or an especially busy day--in fact it seems that the only consistent factor of the day that precedes it is that the day is very normal.

Aside from that night however, I never really have trouble sleeping. If I'm up around 6 (as my work day schedule demands) I'll comfortably drop off around 10. It doesn't matter if I've just insulted my boss, lost a valuable document, had my wallet stolen, argued with one of my girls or inadvertently run over the world's cutest chipmunk on the way home. It doesn't matter if my actions have been vicious or kind, simple or complicated. I sleep the sleep of an innocent baby when I'm ready.

And the next morning I wake up refreshed, usually from a sleep that is more dreamless the meaner I've been the previous day.

Should that worry me?