Public Release:  Under a cloud -- darkness linked to 'brain drain' in depressed people

BioMed Central

A lack of sunlight is associated with reduced cognitive function among depressed people. Researchers writing in BioMed Central's open access journal Environmental Health used weather data from NASA satellites to measure sunlight exposure across the United States and linked this information to the prevalence of cognitive impairment in depressed people.

Shia Kent, from the University of Alabama at Birmingham, led a team of US researchers who used cross-sectional data from 14,474 people in the NIH-NINDS-funded REGARDS study, a longitudinal study investigating stroke incidence and risk factors, to study associations between depression, cognitive function and sunlight. He said, "We found that among participants with depression, low exposure to sunlight was associated with a significantly higher predicted probability of cognitive impairment. This relationship remained significant after adjustment for season. This new finding that weather may not only affect mood, but also cognition, has significant implications for the treatment of depression, particularly seasonal affective disorder".

Kent and his colleagues speculate that the physiological mechanisms that give rise to seasonal depression may also be involved in sunlight's effect on cognitive function in the context of depressive symptoms. Cognitive function was assessed by measurement of short-term recall and temporal orientation. As well as regulating the hormones serotonin and melatonin, light has been shown to also affect brain blood flow, which has in turn been linked with cognitive functions. The researchers write, "Discovering the environment's impact on cognitive functioning within the context of seasonal disorders may lead not only to better understanding of the disorders, but also to the development of targeted interventions to enhance everyday functioning and quality of life".


Notes to Editors

1. Effect of sunlight exposure on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study
Shia T Kent, Leslie A McClure, William L Crosson, Donna K Arnett, Virginia G Wadley and Nalini Sathiakumar
Environmental Health (in press)

During embargo, article available here:
After the embargo, article available at journal website:

Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central's open access policy.

Article citation and URL available on request at on the day of publication

2. Environmental Health is an open access, peer-reviewed, online journal that considers manuscripts on all aspects of environmental and occupational medicine, and related studies in toxicology and epidemiology. It is aimed at scientists and practitioners in all areas of environmental science where human health and well-being are involved, either directly or indirectly. Environmental Health is a public health journal serving the public health community and scientists working on matters of public health interest and importance pertaining to the environment.

3. BioMed Central ( is an STM (Science, Technology and Medicine) publisher which has pioneered the open access publishing model. All peer-reviewed research articles published by BioMed Central are made immediately and freely accessible online, and are licensed to allow redistribution and reuse. BioMed Central is part of Springer Science+Business Media, a leading global publisher in the STM sector.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.