It's kind of cute but slightly sad at the same time, well maybe not sad exactly but I kind of feel sorry for him a bit:

Poor baby! I feel so sorry for him when he bangs his head.

This reminds me of REM Sleep Behavior Disorder in humans, which can be a sign of impending Parkinson's disease.

It also looks like he might be having epileptic seizures.

I hope his owner has taken him to a vet and is taking good care of him. If it were my dog, I would be very worried.

Wow! That pooch needs medication. I'd worry about him getting violent in that state, especially if he's sleep deprived to begin with.

Hopefully, there aren't any small children or other pets around when he sleeps and he can't fall down stairs or anything like that.

I'd love to see what he's dreaming about, he might be having the time of his life.

I hope so, but I'm still worried.