The nighttime habit linked to depression
Now that it's getting darker earlier, most of us flick on every light switch in the house when we get home at night—right before booting up the computer for an after-hours Facebook session. Unfortunately, that nighttime routine could be doing your health a serious disservice: Spending evenings bathed in artificial light might actually trigger depression and cognitive decline, according to new research.
In a study published in the journal Nature, investigators exposed mice to a cycle of light and dark that didn’t disrupt the creatures’ natural sleep cycle. Research has already shown that artificial light interferes with sleep, so the study was designed to examine how this light impacts mental health, minus the low-quality zzzs.
Turns out, that impact is pretty darn scary: Exposure to light during the lead-up to sleep triggers changes in key brain regions responsible for mood, memory and learning—and, as a result, causes depressive behaviors and impaired learning capacity among mice.
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And for the non-rodent among us, it's not good either. “Mice and humans actually have very similar retinal cells that are activated by light,” says study co-author Samer Hattar, PhD, professor of biology at Johns Hopkins University. “[But] we’ve never appreciated before how important these cells are in depression and cognition.”
To minimize the risks of excess nighttime light, Hattar recommends rethinking your day-to-day routine. “Make a point of getting outside during the day, to get plenty of natural sunshine,” he says. Once the sun sets, his advice is simple: Dim the lights at home, or opt for lamps or candles instead of overhead bulbs.
If you can resist the lure of the web, try some new hobbies—old-fashioned reading, at-home yoga—that don’t involve bright screens. But if you’ve gotta log on, Hattar suggests dimming your screen as much as possible. “Experiment to see the minimum amount of light you need to work and read,” he says. “People would be really surprised at how little is actually necessary.”
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Published November 2012, Prevention