I'm gonna jump on your 6yo post because it came up when I searched for "why do I stutter when I'm tired?" I normally have zero stutter, but occasionally, like this morning, I wake up after a short night of sleep and stutter my way through the morning. It usually goes away fairly quickly after I take my ADHD meds, but at times can persist for a few hours. I just Google it this morning because it was particularly bad. Neat story: My father had a severe stutter as a child, which they believed was possibly due to the fact that he was the 2nd twin and they had to use forceps to aid in his birth (he was born in 1944). He had this stutter until 8 or 9 years old when his younger brother, the family miracle worker, threw a brick that hit him in the head. It didn't fix his lazy eye, but he never stuttered after that. Doctors suspect that it released some cranial pressure from his birthing experience.