title: Biological rhythms: Human sleep before the industrial era.
authors.affiliation: Surrey Sleep Research Centre, University of Surrey, Guildford GU2 7XP, UK.
authors.forename: Derk-Jan
authors.initials: DJ
authors.lastname: Dijk
authors.affiliation: Department of Mathematics, University of Surrey, Guildford GU2 7XP, UK.
authors.forename: Anne C
authors.initials: AC
authors.lastname: Skeldon
mesh_terms: D002940:Circadian Rhythm; D006801:Humans; D010507:Periodicity; D012890:Sleep