WEDNESDAY, Nov. 14 (HealthDay News) -- A new study suggests that when the sun goes down, you might end up happier and better able to learn new things if you turn down all the lights -- even your computer screen.
Unfortunately, the research was done just with mice. But because they share the same set of special light-activated cells in their eyes that humans have -- known as ipRGCs -- it may be that the comparisons could apply to people.
Those cells, called intrinsically photosensitive retinal ganglion cells, are stimulated by bright light, which affects the brain's mood, memory and learning centers, the researchers said.
The study found that chronic exposure to bright light at night elevates cortisol, a stress hormone that can cause depression and reduce thinking function.
"Expose yourself to bright light in the day and avoid it at night," suggested study co-author Samer Hattar, an associate professor of biology and neuroscience at Johns Hopkins University, in Baltimore. "That will keep the ipRGCs that affect mood from being activated."
The research was published online in the Nov. 14 in the journal Nature.
Hattar said the research team was initially interested in whether seasonal affective disorder (SAD) -- a form of depression people sometimes experience in the lower-light winter months -- applied to mice. They exposed mice to an alternating cycle of 3.5 hours of light and then 3.5 hours of darkness. The mice got depressed.
How do you know that a mouse is sad? They take less interest in sugar and move less in the cage, and they have trouble learning and remembering, Hattar explained. When the mice were given Prozac (fluoxetine), a commonly prescribed antidepressant, their symptoms went away.
To understand the role of the retina's neurological circuits in affecting mood, memory and learning, the researchers studied animals
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