Light at night likely has unspecified biological consequences.

Throughout their history, both humans and nonhuman animals experienced dark nights. This began to change ~120 years ago with the development of electric lighting which illuminates our nights and most recently has led to urban and suburban light pollution. Normal physiology and behavior have a circadian organization that depends on clear light and dark signals, but the presence of light at night potentially disrupts this temporal organization. Because of the convenience of electric lights and their widespread use prior to an understanding of the importance of circadian rhythms to health, little thought has been given to their biological effects. 

Our research and others have identified major biological and medical consequences of being exposed to light during the night including the development of obesity and diabetes, immunological dysfunction, depression, anxiety, and vulnerability to cardiovascular disease in rodents.  This website has been established to help educate the general public about the role of light at night in health and disease.  

Light during the night comes from two general sources.  First, light pollution from urban and suburban centers can prevent the night from ever becoming fully dark.  Additionally, the proliferation of indoor lights and light-emitting electronic devices inside our homes can prevent our bodies from experiencing natural cycles of light and dark. 

https://www.register-herald.com/health/wvu-researcher-suggests-limiting-exposure-to-light-at-night-for/article_4a602bbb-1731-541a-a0b8-d6ece58510d7.html

https://www.youtube.com/watch?v=omwX4MzsQxI

https://www.thelantern.com/2013/09/ohio-state-study-finds-blue-white-lighting-causes-depression/

https://www.themarysue.com/study-finds-too-much-light-at-night-may-lead-to-obesity/

https://thriveglobal.com/stories/for-better-health-think-paleo-lighting/

https://www.sciencedaily.com/releases/2010/11/101117184350.htm

https://abc6onyourside.com/news/local/study-health-problems-from-nighttime-light-exposure-can-be-passed-to-offspring

https://www.sleepfoundation.org/articles/too-much-light-night-may-cause-depression

https://gunnar.com/is-blue-light-from-screens-wrecking-your-sleep/

https://medicalxpress.com/tags/light+pollution/

https://www.eurekalert.org/pub_releases/2017-02/uoca-cgt020217.php

https://www.everydayhealth.com/sleep/everything-you-need-know-about-your-circadian-rhythm/

https://wvutoday.wvu.edu/stories/2019/04/03/wvu-researchers-identify-how-light-at-night-may-harm-outcomes-in-cardiac-patients

1.  Russart, K.L.G., Chbeir, S., Nelson, R.J. & Magalang, U. 2019. Light at night exacerbates metabolic dysfunction in a polygenic mouse model of type 2 diabetes mellitus. Life Sciences (In press). doi: 10.1016/j.lfs.2019.116574

2.       Walker, W.H., Zhang, N., Melendez-Hernandez, O.H., Pascoe, J., DeVries, A.C., & Nelson, R.J. 2019. Acute exposure to dim light at night is sufficient to induce neurological changes and depressive-like behavior. Molecular Psychiatry (In press). DOI: 10.1038/ s41380-019-0430-4

3.       Fonken LK, Bedrosian TA, Zhang N, Weil ZM, DeVries AC, Nelson RJ. 2019. Dim light at night impairs recovery from global cerebral ischemia. Experimental Neurology, 317:100-109. doi: 10.1016/j.expneurol.2019.02.008. PMID: 30822422 

4. Dominoni DM, Nelson RJ.  2018. Artificial light at night as an environmental pollutant: An integrative approach across taxa, biological functions, and scientific disciplines.  Journal of Experimental Zoology A,  329: 387-393. doi: 10.1002/jez.2241. PMID: 30371014

5. Emmer KM, Russart KLG, Walker WH, Nelson RJ, DeVries AC. 2018. Effects of light at night on laboratory animals and research outcomes.  Behavioral Neuroscience, 132:302-314. doi: 10.1037/bne0000252.  PMID: 29952608 

6. Russart KLG, Nelson RJ.  2018. Artificial light at night alters behavior in laboratory and wild animals.

Journal of Experimental Zoology A, 329:401-408. doi: 10.1002/jez.2173. PMID: 29806740 

7. Nelson RJ, Chbeir S. 2018. Dark matters: effects of light at night on metabolism.  Proceedings of the Nutrition Society, 77:223-229. doi: 10.1017/S0029665118000198. PMID: 29747703 

8. Russart KLG, Nelson RJ.  Light at night as an environmental endocrine disruptor. Physiology & Behavior, 190:82-89. doi: 10.1016/j.physbeh.2017.08.029. PMID: 28870443 

9. Lunn RM, Blask DE, Coogan AN, Figueiro MG, Gorman MR, Hall JE, Hansen J, Nelson RJ, Panda S, Smolensky MH, Stevens RG, Turek FW, Vermeulen R, Carreón T, Caruso CC, Lawson CC, Thayer KA, Twery MJ, Ewens AD, Garner SC, Schwingl PJ, Boyd WA.  2017. Health consequences of electric lighting practices in the modern world: A report on the National Toxicology Program's workshop on shift work at night, artificial light at night, and circadian disruption.  Science of the Total Environment, 607-608:1073-1084. doi: 10.1016/j.scitotenv.2017.07.056. PMID: 28724246 

10. Cissé YM, Russart KLG, Nelson RJ. 2017. Depressive-like behavior is elevated among offspring of parents exposed to dim light at night prior to mating.  Psychoneuroendocrinology, 182-186. doi: 10.1016/j.psyneuen.2017.06.004.  PMID: 28644985 

11. Cissé YM, Peng J, Nelson RJ.  2017. Effects of dim light at night on food intake and body mass in developing mice.  Frontiers in Neuroscience, 11:294. doi: 10.3389/fnins.2017.00294.  PMID: 28603481 

12. Cissé YM, Russart KL, Nelson RJ. 2017. Parental exposure to dim light at night prior to mating alters offspring adaptive immunity. Scientific Reports, 7:45497. doi: 10.1038/srep45497. PMID: 28361901 

13. Cissé YM, Peng J, Nelson RJ.  2016.  Dim light at night prior to adolescence increases adult anxiety-like behaviors. Chronobiology International, 33:1473-1480.  PMID: 27592634 

14. Dominoni DM, Borniger JC, Nelson RJ.  2016. Light at night, clocks and health: from humans to wild organisms.  Biology Letters, 12:20160015. doi: 10.1098/rsbl.2016.0015. PMID: 26888917

15. Hogan MK, Kovalycsik T, Sun Q, Rajagopalan S, Nelson RJ.  2015. Combined effects of exposure to dim light at night and fine particulate matter on C3H/HeNHsd mice.  Behavioural Brain Research, 294:81-8. doi: 10.1016/j.bbr.2015.07.033. PMID: 26235330 

16. Aubrecht TG, Jenkins R, Nelson RJ.  2015. Dim light at night increases body mass of female mice. 

Chronobiology Internation, 32:557-560. doi: 10.3109/07420528.2014.986682. PMID: 25431079 

17. Aubrecht TG, Weil ZM, Nelson RJ.  2014. Dim light at night interferes with the development of the short-day phenotype and impairs cell-mediated immunity in Siberian hamsters (Phodopus sungorus).   Journal of Experimental Zoology A, 321:450-456. doi: 10.1002/jez.1877. Epub 2014 Jun 24. PMID: 24962267 [PubMed - indexed for MEDLINE]

18. Borniger JC, Maurya SK, Periasamy M, Nelson RJ.  2014. Acute dim light at night increases body mass, alters metabolism, and shifts core body temperature circadian rhythms. Chronobiology International, 31:917-925. doi: 10.3109/07420528.2014.926911.  PMID: 24933325 

19. Borniger JC, McHenry ZD, Abi Salloum BA, Nelson RJ.  2014. Exposure to dim light at night during early development increases adult anxiety-like responses. Physiology & Behavior, 133:99-106. doi: 10.1016/j.physbeh.2014.05.012.  PMID: 24857721 

20. Fonken LK, Nelson RJ.  2014. The effects of light at night on circadian clocks and metabolism.  Endocrine Reviews, 35:648-670. doi: 10.1210/er.2013-1051.  PMID: 24673196 

21.   Ikeno T, Weil ZM, Nelson RJ.  2014. Dim light at night disrupts the short-day response in Siberian hamsters. General and Comparative Endocrinology, 197:56-64. doi: 10.1016/j.ygcen.2013.12.005. 

PMID: 24362257 

22. Fonken LK, Meléndez-Fernández OH, Weil ZM, Nelson RJ. 2014.  Exercise attenuates the metabolic effects of dim light at night.  Physiology & Behavior, 124:33-36. doi: 10.1016/j.physbeh.2013.10.022.  PMID: 24184414 

23. Fonken LK, Weil ZM, Nelson RJ.  2013.  Mice exposed to dim light at night exaggerate inflammatory responses to lipopolysaccharide.  Brain, Behavior and Immunity, 34:159-163. doi: 10.1016/j.bbi.2013.08.011.  PMID: 24012645 

24. Fonken LK, Aubrecht TG, Meléndez-Fernández OH, Weil ZM, Nelson RJ.  2013.  Dim light at night disrupts molecular circadian rhythms and increases body weight.  Journal of Biological Rhythms, 28:262-271. doi: 10.1177/0748730413493862. PMID: 23929553 

25. Fonken LK, Lieberman RA, Weil ZM, Nelson RJ. 2013. Dim light at night exaggerates weight gain and inflammation associated with a high-fat diet in male mice.  Endocrinology, 154:3817-3825. doi: 10.1210/en.2013-1121.  PMID: 23861373 

26. Borniger JC, Weil ZM, Zhang N, Nelson RJ.  2013. Dim light at night does not disrupt timing or quality of sleep in mice. Chronobiology International, 30:1016-1023. doi: 10.3109/07420528.2013.803196. 

PMID: 23837748 

27. Bedrosian TA, Aubrecht TG, Kaugars KE, Weil ZM, Nelson RJ.  2013. Artificial light at night alters delayed-type hypersensitivity reaction in response to acute stress in Siberian hamsters. Brain, Behavior and Immunity,  34:39-42. doi: 10.1016/j.bbi.2013.05.009. PMID: 23743259 

28. Aubrecht TG, Weil ZM, Magalang UJ, Nelson RJ.  2013. Dim light at night interacts with intermittent hypoxia to alter cognitive and affective responses. American Journal of Physiology, 305:R78-86. doi: 10.1152/ajpregu.00100.2013. . PMID: 23657638 

29. Fonken LK, Nelson RJ.  2013. Dim light at night increases depressive-like responses in male C3H/HeNHsd mice. Behavioral Brain Research, 243:274-8. doi: 10.1016/j.bbr.2012.12.046. 

PMID: 23291153 

30. Bedrosian TA, Weil ZM, Nelson RJ.  2012. Chronic citalopram treatment ameliorates depressive behavior associated with light at night. Behavioral Neuroscience, 126:654-658. doi: 10.1037/a0029699. PMID: 22889310 

31. Fonken LK, Haim A, Nelson RJ.  2012. Dim light at night increases immune function in Nile grass rats, a diurnal rodent.  Chronobiology International, 29:26-34. doi: 10.3109/07420528.2011.635831. Erratum in: Chronobiol Int. 2012 May;29(4):530. PMID: 22217098

32. Fonken LK, Nelson RJ.  2011. Illuminating the deleterious effects of light at night. F1000 Medical Reports, 3:18. doi: 10.3410/M3-18.  PMID: 21941596 

33. Zubidat AE, Nelson RJ, Haim A. 2011.  Spectral and duration sensitivity to light-at-night in 'blind' and sighted rodent species. Journal of Experimental Biology, 214:3206-3217. doi: 10.1242/jeb.058883. PMID: 21900468 

34. Bedrosian TA, Fonken LK, Walton JC, Haim A, Nelson RJ.  2011. Dim light at night provokes depression-like behaviors and reduces CA1 dendritic spine density in female hamsters. Psychoneuroendocrinology, 36:1062-1069. doi: 10.1016/j.psyneuen.2011.01.004.  PMID: 21292405 

35. Bedrosian TA, Fonken LK, Walton JC, Nelson RJ. 2011. Chronic exposure to dim light at night suppresses immune responses in Siberian hamsters.  Biology Letters, 7:468-471. doi: 10.1098/rsbl.2010.1108. PMID: 21270021 

36. Fonken LK, Workman JL, Walton JC, Weil ZM, Morris JS, Haim A, Nelson RJ.  2010. Light at night increases body mass by shifting the time of food intake. Proc Natl Acad Sci U S A., 107:18664-18669. doi: 10.1073/pnas.1008734107. PMID: 20937863 

37. Fonken LK, Finy MS, Walton JC, Weil ZM, Workman JL, Ross J, Nelson RJ.  2009. Influence of light at night on murine anxiety- and depressive-like responses. Behavioural Brain Research, 205:349-54. doi: 10.1016/j.bbr.2009.07.001.  PMID: 19591880 

38. Navara KJ, Nelson RJ. 2007. The dark side of light at night: physiological, epidemiological, and ecological consequences. Journal of  Pineal Research, 43:215-224.  PMID: 17803517