Dreams can screw with your head

Have you ever had a super-duper realistic feeling dream, where something horrible happens, or someone you know does something that really upsets you? Then you awake, and you're not quite sure if that was a dream or if it really happened. Not only is it an awful start to the morning, but this can often stick with you and bug you the rest of the day. It just keeps gnawing at you--was that real? Did that really happen? And you want to be mean to that person who wronged you in the dream, but really in all fairness you can't. It's so weird how dreams can screw with you like this.

But I guess at least we can tell the difference between dreams and reality (at least most of us). What about animals? Let's say a dog has a really bad dream where his master has been hitting him or something. When that dog wakes, does he know that it was just a dream and not reality? Or does the dog really think his master was hitting him. Next time your pet acts in an unpredictable way against you, think twice before getting upset. Maybe the pet was just reacting to some dream he or she had.

On the other hand, maybe most animals don't remember dreams the way us more intelligent species do. Maybe they have never evolved to be able to do this. That would be a good safety measure for animals that can't tell that their dreams are not real.