WE have a tupperwear type cup for my daughter at bed.  I want her to always be able to have water.  When she was younger she had a sippie cup.  the one she has now is a closed container with a flip up type of "straw" that she gets water out of.  I fill it each night.  Sometimes, by morning it is 1/2 to all the way empty.  I say she needs it!  Julia