A video of what appears to be a sleeping woman doing a modified, slow-motion funky robot dance in bed may represent the most direct evidence yet that minds replay a day’s learning during slumber.
Much research supports this hypothesis, which in recent years has eroded the classical conviction that sleeping minds were, if not empty vessels, blank slates for undirected neurological activity. When tested on new facts, people remember them better after a good night’s sleep than a short break. Brain imaging shows similar patterns in their sleeping brains as when they are learning. But while compelling, such demonstrations are indirect.
To avoid ambiguity, sleep researcher Delphine Oudiette of France’s Université Pierre et Marie Curie-Paris and colleagues devised a cleverly straightforward test: They would teach a motor task to sleepwalkers and people with sleep behavior disorders, who typically move their bodies in tandem with dreams. If test subjects repeated the motions while sleeping, it would clearly demonstrate replay.
Oudiette’s team describes the experiment Mar. 21 in Public Library of Science ONE. Participants were trained to hit an array of color-coded buttons in response to computer prompts, then taped while asleep. Taken in aggregate, their sleeping movements tended to resemble those in the test. One woman in particular performed the test choreography with uncanny precision.
“To our knowledge, the present findings represent the first direct and unambiguous demonstration of overt behavioral replay of a recently learned skill during human sleep,” wrote the researchers, who suggest that testing motor behavior in people with sleep disorders could provide “highly valuable information about cognitive and motor processes occurring during sleep.”
So take solace, somnambulants. For all the difficulties and embarrassments your condition may have caused, you could be quite valuable to science. But be careful with those evening karate classes.
Video: A sleepwalking test subject learns a motor task while awake; repeats the actions while lying awake in bed; and is seen going through the motions in her sleep./Delphine Oudiette, PLoS ONE.
PLoS one, 2011. DOI: 10.1371/journal.pone.0018056 (About DOIs).
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