Not quite the same thing, but I sometimes seem to think while I'm asleep, very close to normal thinking while I'm awake. I know this because occasionally I wake up while I'm thinking and realize I was thinking in a rational way rather than dreaming or experiencing hypnogogic imagery. I suppose if I can do this, it would only be a short step to thinking I was already awake and doing things.

Also, I often oversleep, but not by very long. After about 30 minutes I get anxious and realize I need to wake up. I take a long time to wake up, and I wake up with cramps and soreness that take about 90 minutes to wear off, so I set my alarm accordingly. So oversleeping by 30 minutes isn't that big a deal.