http://www.babyssb.co.jp/shopping/innner/084010.html
I don't know if I want to spend that much on something I'd only wear to bed... I guess the obvious solution is to make your own, since they don't look overly complicated. There were patterns in some of the GLBs to make nightwear, but I haven't really seen any for sale until now. Have other brands made nighties as well?