title: Evening exposure to blue light stimulates the expression of the clock gene PER2 in humans.
abstract: We developed a non-invasive method to measure and quantify human circadian PER2 gene expression in oral mucosa samples and show that this gene oscillates in a circadian (= about a day) fashion. We also have the first evidence that induction of human PER2 expression is stimulated by exposing subjects to 2 h of light in the evening. This increase in PER2 expression was statistically significant in comparison to a non-light control condition only after light at 460 nm (blue) but not after light exposure at 550 nm (green). Our results indicate that the non-image-forming visual system is involved in human circadian gene expression. The demonstration of a functional circadian machinery in human buccal samples and its response to light opens the door for investigation of human circadian rhythms at the gene level and their associated disorders.
authors.affiliation: Centre for Chronobiology, Psychiatric University Clinics, University of Basel, CH-4025 Basel, Switzerland. christian.cajochen@unibas.ch
authors.forename: Christian
authors.initials: C
authors.lastname: Cajochen
authors.forename: Corinne
authors.initials: C
authors.lastname: Jud
authors.forename: Mirjam
authors.initials: M
authors.lastname: Münch
authors.forename: Szymon
authors.initials: S
authors.lastname: Kobialka
authors.forename: Anna
authors.initials: A
authors.lastname: Wirz-Justice
authors.forename: Urs
authors.initials: U
authors.lastname: Albrecht
mesh_terms: D000328:Adult; D003116:Color; D003624:Darkness; D004307:Dose-Response Relationship, Radiation; D005260:Female; D015870:Gene Expression / Q000528:radiation effects*; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism; D009092:Mucous Membrane / Q000378:metabolism / Q000528:radiation effects; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D056950:Period Circadian Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D009687:Nuclear Proteins; C421902:PER2 protein, human; D056950:Period Circadian Proteins; D014157:Transcription Factors; D008550:Melatonin