Good sleep is an essential prerequisite for the ability to concentrate. But how can the quality of sleep be measured? In order to answer this question, Levin Burghardt (14), Niklas Sander (15) and Moritz Ellermann (15) from Dortmund investigated various aspects - such as the phases of sleep experienced during the night. They used a self-made measuring device to monitor eye movements during sleep. A sensor attached to the wrist measures the pulse, while software they developed themselves records data on humidity and temperature. In future, this invention could provide an alternative to expensive examinations in a sleep laboratory.