optogenetics (IMAGE) University of Bern Caption A technique called optogenetics can be used to study brain activity during REM sleep. Credit Pascal Gugler / Insel Gruppe Usage Restrictions Credit must be given to the creator. License CC BY 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.