Left brain stands guard while sleeping away from home

Enhanced sensitivity to sound may serve as safety measure

resting person

RESTING UNEASY  Part of the left brain remains vigilant while sleeping in a strange place, a new study suggests. 

KatarzynaBialasiewicz/iStockphoto

Away from home, people sleep with one ear open.

In unfamiliar surroundings, part of the left hemisphere keeps watch while the rest of the brain is deeply asleep, scientists report April 21 in Current Biology.