When you're in a relationship with someone and you need a few hours to take a little space to relax or work and do things independently. Ideally, this in no way threatens the relationship or means you love them less.
"Hey babe, it's been a long day. You mind if I take a little bubbletime and play a game for a few hours?"
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.