Light therapy can help improve the mood of people with seasonal affective disorder (SAD) during the short winter days, but it is not well understood how this therapy works. A new study by Urs Albrecht at the University of Freiburg, published on July 8 in the journal PLOS Genetics, notes that the beneficial effects of light therapy come from the activation of the Period1 circadian clock gene in a part of the brain involved in mood and sleep-wake cycles.
Night light has strong effects on the physiology and behavior of mammals. It can restore the circadian rhythms of an animal and in the form of light therapy, affect the mood of humans. Albrecht and colleagues investigated how night light affects mood using mice as a model. They exposed the mice to a pulse of light at different points in the night and then tested their depressive behavior. The researchers found that exposure to light at the end of the dark period (two hours before the day) had an antidepressant effect on the animals. The light pulse activated the Period1 gene in a region called the brain lateral habenula, which plays a humorous role. The light at other times, however, had no effect. When they removed the Period1 gene, the mice no longer experienced light beneficial effects.
The new results provide evidence that activating Period1 in the lateral habit is the key to the powers that increase the mood of light. The discovery that mice appeared to be less depressed when exposed to light at the end of the dark period that the onset is similar to the discoveries in humans. Light therapy is more efficient in the early morning than at night for patients with SAD. However, researchers warn not to make too many direct comparisons with humans as mice are nocturnal animals.
The researchers add: “Perceived light at the end of the night induces the expression of the Per1 clock gene, which is related to the improvement of depression as the behavior of mice.”
Olejniczak I, Ripperger JA, Sandrelli F, Schnell A, Mansencal-Strittmatter L, Wendrich K, et al. (2021) Light affects behavioral despair affecting the clock gene Period 1. PLoS Genet 17 (7): e1009625. doi.org/10.1371/journal.pgen.1009625
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CitationScientists show how light therapy treats depression in the mouse model (2021, July 8) retrieved July 8, 2021 at https://medicalxpress.com/news/2021-07-scientists-therapy-depression -mice.html
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