Animals and Dreams

We can’t be 100% sure that animals dream in a similar way as humans, but they do enter into a state of REM sleep. REM sleep occurs in all mammals, although it excludes the egg-laying monotremes of Australia. The sentinel hypothesis of REM sleep, which was put forward by Frederic Snyder in 1966, proposes that many mammals wake-up immediately after entering into REM sleep, leading him to infer that the process was being used as a defense mechanism. Many birds also show signs of REM sleep, but reptiles and other cold-blooded animals do not. The echidna does enter into REM sleep, but only if its environment is around 25°C. Dogs and cats also experience this stage of sleep. - By BryanJ / Source: The List Universe