Fluent when you wake up?

Fluent when you wake up? I just noticed the moment I wake up from sleeping I am 100% fluent and I can hold entire conversation no problem. This really happened a lot when I talk to my family in early morning so I thought there is connection and not just coincidence/luck. But once I regain my full consciousness *if that's the correct phrasing* My stutter gets back again (severe blocks) . Is that only happens with me ? *English isn't my mother language btw*