Does it often seem to you that your "significant other"  woke up on the wrong side of the bed? Are you often mystified by this? I'm "just a guy" & wouldn't begin to represent that I have women figured out. Maybe you did something "wrong."

On the other hand, you might try taking steps to help her get more sleep.
Women reportedly suffer more ill effects from sleep deprivation than men. Research also indicates they need more sleep than men to begin with. That makes them more likely to be grumpy, and hostile in the morning.

Experts usually recommended around seven hours of shut-eye per night. If a woman isn't getting enough sleep, (most Americans aren’t), crankiness is the least of your worries.   Sleep deprivation increases the risk of heart disease, (the #1 killer of women in the US) stroke and depression. So, if you love someone let them sleep!