title: The day within.
authors.affiliation: Centre for Chronobiology, Institute for Medical Psychology, Medical Faculty, Ludwig-Maximilians-University, Munich, Germany. till.roenneberg@imp.med.uni-muenchen.de
authors.forename: Till
authors.initials: T
authors.lastname: Roenneberg
mesh_terms: D000818:Animals; D001683:Biological Clocks; D035843:Biomedical Research / Q000266:history; D002940:Circadian Rhythm; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans