Last week, just as I was drifting off to sleep, my dog Rowdy made a weird noise. He was almost barking, but not quite. It startled me awake and, adrenaline slightly pumping, I was more alert when he then did it a second time. It was a weird noise, something like "berf." Like he was trying to bark without opening his mouth. I realized that he wasn't dying, nor had he heard an intruder downstairs. He was barking in his sleep.

Any of you who have pets, dogs especially, have probably noticed something like this. Dogs pretty regularly start twitching their legs while they sleep, or even moving them as if they're running. Our reaction is always "Aww, he's dreaming!" Well, that was my reaction the night of the berfs. But it got me wondering: do we really know if dogs dream? And how much do we know about it if they do?