Triggering REM Sleep in Mice (IMAGE) University of California - Berkeley Caption When a laser triggers an optogenetic switch in neurons in the medulla of a sleeping mouse, the animal goes from non-REM sleep (NREM) into REM or dream sleep. The axons of these neurons (green) reach into distant parts of the primitive brain, such as the hypothalamus, broadly affecting brain function. Credit Franz Weber/UC Berkeley Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.