I'm a big fan of Yogi teas. I like their night time teas and their digestive teas (they make a number of different ones. I do think herbal teas, no matter the brand really, do work and can at least help you feel better. I like the lemon ginger teas when I have a cold. If you can get your hands on, or make, Korean Saenggang Cha (ginger/honey tea), when you've got a cold, that's the best! It often comes in a jar and has texture like a jam or marmalade. You just get a spoonful or so, and pour boiling water over it. It's delicious and does help clear your head when it's stuffed up.
I'm not a big fan of plain old water, so often find myself drinking different herbal teas throughout the day instead and at night too. I don't mind if they get cold.