A contraction of "for" and "that": "for that". The media has blitzed us with the phrase "for that". It has become so common to link the word that it has created its own contraction.
Either liquid niquil or any liquid drink with melatonin, Ashwaganda or other sleeping aids in a liquid form. If warm tea helps you get to sleep that could be sleepy juice too.
I could not sleep so I chugged some sleepy juice and now I'm so tired and sleepy.