Oh, I've never done this. Have to try it soon! I've had oatmilk creamer in my coffee though, and I liked it.
By the way, insomnia is awful. I have no problems with coffee, but green tea and black tea will probably make me stay awake all night long 🥱 a little sleepy, yet unable to sleep.
In both cases I prefer not to risk staying up all night for no good reason 😃 I prefer to drink coffee during the day ☕.