Disclosure: The authors declare no conflicts of interest.
Dark nights reverse metabolic disruption caused by dim light at night
Version of Record online: 10 MAY 2013
Copyright © 2013 The Obesity Society
Volume 21, Issue 6, pages 1159–1164, June 2013
How to Cite
Fonken, L.K., Weil, Z.M. and Nelson, R.J. (2013), Dark nights reverse metabolic disruption caused by dim light at night. Obesity, 21: 1159–1164. doi: 10.1002/oby.20108
Funding agencies: This research was supported by a grant from the National Science Foundation to RJN and an American Heart Association Predoctoral Fellowship to LKF.
- Issue online: 26 JUL 2013
- Version of Record online: 10 MAY 2013
- Accepted manuscript online: 5 NOV 2012 05:51PM EST
- Manuscript Accepted: 5 SEP 2012
- Manuscript Received: 16 JUL 2012
- National Science Foundation to RJN and an American Heart Association Predoctoral Fellowship to LKF
The increasing prevalence of obesity and related metabolic disorders coincides with increasing exposure to light at night. Previous studies report that mice exposed to dim light at night (dLAN) develop symptoms of metabolic syndrome. This study investigated whether mice returned to dark nights after dLAN exposure recover metabolic function.
Design and Methods
After 4 weeks in their respective lighting conditions both groups initially placed in dLAN increased body mass gain compared to LD mice. Half of the dLAN mice (dLAN/LD) were then transferred to LD and vice versa (LD/dLAN). Following the transfer dLAN/dLAN and LD/dLAN mice gained more weight than LD/LD and dLAN/LD mice. At the conclusion of the study dLAN/LD mice did not differ from LD/LD mice with respect to weight gain and had lower fat pad mass compared to dLAN/dLAN mice. Compared to all other groups dLAN/dLAN mice decreased glucose tolerance as indicated by an intraperitoneal glucose tolerance test at week 7, indicating that dLAN/LD mice recovered glucose metabolism. dLAN/dLAN mice also increased MAC1 mRNA expression in peripheral fat as compared to both LD/LD and dLAN/LD mice, suggesting peripheral inflammation is induced by dLAN, but not sustained after return to LD.
These results suggest that re-exposure to dark nights ameliorates metabolic disruption caused by dLAN exposure.