It does indeed! Some animals experience sleep cycles quite similar to humans, and even experience REM sleep too. REM (rapid eye movement) sleep is a stage of sleep characterised by random, rapid eye movements, in which we are most likely to dream. Between 20–25% of our night’s sleep is spent in the REM stage.
REM sleep occurs in all land mammals and birds. Anyone who has a dog can infer that they dream—my dog’s paws twitch as though running, and he makes little whining noises as if something awful is happening in his dreams, which is both really cute and quite distressing.
Stanley Coren, psychology professor at the University of British Columbia, has found that canines experience the same basic sleep cycles as humans, only faster—and, apparently, big dogs dream for longer, while little dogs dream quickly and frequently. Monitoring dogs’ brain activity has shown that their brainwave patterns and physical behaviours are pretty similar to human sleep studies, indicating that they are actually dreaming.
It’s thought that in adult humans, dreams stimulate brain regions associated with memories, so REM sleep is important for consolidating memories. Studies on sleeping rats have shown that their brains create distinctive patterns of neurons firing in the hippocampus, which a brain area known to be involved in memory—researchers actually recorded brain activity in rats running complex mazes, then recorded their brain activity again when they were experiencing REM sleep, and the same basic patterns appeared. So it seems that their dreams are connected to actual experiences, and the purpose of t heir dreams might be the same as humans’.
Interestingly, reptiles may experience REM sleep too—some researchers suggest that dreaming among mammals might be a remnant from when our brains were in the early, reptilian stage of evolution.