Why does my dog dream so much?

Dogs dream as often as humans. Don't wake him just like you would want to sleep through your dream! He could be running through fields, chasing cats or rabbits. It's not known if dogs have nightmares or not but dreams are ultimately harmless.

Dogs dream just like humans and since they have more sleep time than humans, they dream more.

Dogs, like people, can have seizures. They also can dream. It’s important for owners to distinguish between seizures and the twitching that commonly occurs when dogs are dreaming. There are some characteristic traits associated with seizures and dreaming that can help differentiate between these two conditions.

I've also read a study about dogs often dreaming of their humans! However, if your dog kicks A LOT and causes himself to fall off the bed or harm himself in some other way, it's best to see your vet because there could be an underlying neurological issue. But otherwise, he should be fine!