I have wavy hair and was wondering what to do with it when I sleep so I don't lose the waves overnight. I tried doing a segmented tail, braiding it, and wearing it lose, and it always ends up looking straighter. (I hope to avoid doing anything with water becuase that just makes it frizzy)
Open band ponytail.
Also, you could just have a shower when you wake up, that will reform the waves.
Yes, having wavy/curly hair myself, that is precisely what I do. Even if not wanting to take a full showing in the morning, a spray bottle with water will do wonders.
I've had that problem too, recently. As skibum said, a few sqirts from a water sprayer does wonders for that. It also helpos with hair oil getting down your hair.