Optogenetics (IMAGE) University of Bern Caption Using a technique called optogenetics, a laser light was used to turn off or on MCH neurons time locked with the temperature warming phases. It demonstrated the necessity of the MCH neurons to increase REM sleep during warming toward 'just right' room temperature. Credit Pascal Gugler for Insel Gruppe AG 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.