great observation. Maybe the sleep quality affects on one capacity of stutter. When I sleep bad it happens the opposite. I stutter like crazy. We can see that there are indirects way that we can treat our stuttering like good sleeping, maybe good nutrition, sports, etc. If we feel good and at ease at general in life maybe we will tend to stutter less, or even if we stutter we will be more supportive so stuttering is less of a threat. Keep on the good work. Observation is the key.