by Virginia Hughes
When I brought my puppy home last August, I knew he would be fun to play with. I had no idea how entertaining he would be when asleep. He dozed constantly, and more often than not, his whole body — legs, tail, lips, eyes, ears — would twitch. This isn’t a quirk of canines. Sleep twitching happens to “literally every mammal that has been looked at”, says Mark Blumberg, a psychology professor at the University of Iowa. Dogs, cats, rats, ferrets, sheep, squirrels — they all twitch. Even whales twitch their flippers. “I have YouTube videos of a guy who recorded his girlfriend’s toes when they twitched,” Blumberg says.
I undoubtedly spent too much time in the past couple of days doing YouTube searches for twitching babies. What’s funny about many of these videos is the commentary of those behind the camera. They tend to say one of two things: “OMG, look at that spaz!” or, “Awww, he’s dreaming.” And that’s how sleep researchers have traditionally thought of twitches, too, according to Blumberg.
“The sleep field really started off in many ways as an offshoot of Freudian psychoanalysis and the study of dreams,” Blumberg says. “People see these movements and they think, ‘Oh, Fido is chasing rabbits in his dreams.’ But it turns out that that’s almost certainly not the case.” In an engaging new review in Current Biology, Blumberg argues that these sleep twitches actually have an indispensible purpose: to teach a newborn what all of its limbs and muscles can do, and how to use them in concert to interact with the big, wide world.
The first big study to propose this idea was published more than 40 years ago in Science. Howard Roffwarg, then director of the Sleep Laboratory at the New York State Psychiatric Institute, described the behaviors and brain-wave patterns of newborn human babies as they sleep. He noted that a newborn spends “one-third of its entire existence” in a REM state, with intense brain activity and continuous muscle contractions.
much more, with cute videos!
http://phenomena.nationalgeographic.com/2013/06/20/why-do-babies-twitch-in-their-sleep-adorable-video-edition/