title: Bright versus dim ambient light affects subjective well-being but not serotonin-related biological factors.
abstract: Light falling on the retina is converted into an electrical signal which stimulates serotonin synthesis. Previous studies described an increase of plasma and CNS serotonin levels after bright light exposure. Ghrelin and leptin are peptide hormones which are involved in the regulation of hunger/satiety and are related to serotonin. Neopterin and kynurenine are immunological markers which are also linked to serotonin biosynthesis. In this study, 29 healthy male volunteers were exposed to bright (5000lx) and dim (50lx) light conditions for 120min in a cross-over manner. Subjective well-being and hunger as well as various serotonin associated plasma factors were assessed before and after light exposure. Subjective well-being showed a small increase under bright light and a small decrease under dim light, resulting in a significant interaction between light condition and time. Ghrelin concentrations increased significantly under both light conditions, but there was no interaction between light and time. Correspondingly, leptin decreased significantly under both light conditions. Hunger increased significantly with no light-time interaction. We also found a significant decrease of neopterin, tryptophan and tyrosine levels, but no interaction between light and time. In conclusion, ambient light was affecting subjective well-being rather than serotonin associated biological factors.
authors.affiliation: Department of General and Social Psychiatry, Center of Psychiatry and Psychotherapy, Austria.
authors.forename: Bettina
authors.initials: B
authors.lastname: Stemer
authors.affiliation: Department of Internal Medicine I, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Melmer
authors.affiliation: Division of Biological Chemistry, Biocenter, Medical University Innsbruck, Austria.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Fuchs
authors.affiliation: Department of Internal Medicine I, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Ebenbichler
authors.affiliation: Department of General and Social Psychiatry, Center of Psychiatry and Psychotherapy, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Kemmler
authors.affiliation: Department of General and Social Psychiatry, Center of Psychiatry and Psychotherapy, Austria. Electronic address: eberhard.deisenhammer@i-med.ac.at.
authors.forename: Eberhard A
authors.initials: EA
authors.lastname: Deisenhammer
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood*; D018592:Cross-Over Studies; D054439:Ghrelin / Q000097:blood; D064368:Healthy Volunteers; D006801:Humans; D006815:Hunger / Q000502:physiology; D020738:Leptin / Q000097:blood; D008029:Lighting / Q000009:adverse effects*; D008297:Male; D012701:Serotonin / Q000097:blood*; D013997:Time Factors; D014364:Tryptophan / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; D054439:Ghrelin; D020738:Leptin; D012701:Serotonin; D014364:Tryptophan
keywords: Ghrelin; Immunological factors; Leptin; Light; Serotonin