Circadian rhythm

I am grateful for circadian rhythm.  If you don't know what that is...it's basically your biological clock.  No matter how much sleep I get or how late I sleep in, if I have to wake up to an alarm I am ornery.  Not for the whole day, but it definitely doesn't help my day.  I get over it within 1/2 hour or sooner.  That's precisely why I'm grateful for the mornings I wake up naturally.  It makes things much more wonderful for me.