Is sleep high a thing?

I'm curious, have you ever heard of the concept of 'sleep high'? Is it a real thing, or just a phrase people use? I've seen it mentioned in some online forums and social media posts, but I'm not sure if it's actually a scientifically recognized phenomenon. Could you enlighten me on this topic? Is there any evidence to support the idea that people can experience heightened feelings of well-being or creativity while they're sleeping? Or is it just a matter of personal interpretation and anecdotal experiences?