Human are diurnal creatures, which means that we’re programmed to be awake while the sun is shining and sleeping at night. But while we can easily look at our smartphones to tell the time of day, our genes use a far more rudimentary input for time-keeping: The presence or absence of bright light.
Bright light (and particularly blue wavelength light, which the sun emits) has many effects on our bodies. Unfortunately today, our daytime exposure to sun is limited—we’re frequently stuck in our apartments or sitting in cars, to get to our 9-to-5 desk jobs.
Here are 5 incredible health benefits of the sun that will hopefully inspire you to embrace the light of day.
1. It makes your brain work faster.
University of Arizona researchers recently exposed adult volunteers to bright blue light (mimicking the wavelength of sunlight) for 30 minutes, and then looked at their brain activity with an fMRI machine. Bright light exposure seemed to activate subjects’ prefrontal cortex, the region of the brain responsible for “higher order” aspects of cognition including planning, decision making, and even aspects of personality. The light also seemed to sharpen their mental acuity: subjects displayed increased processing speed and reaction times on tests compared to those exposed to amber-colored light. (R)
2. It makes you horny baby, yeah.
A small trial involved 38 fellas who complained of both low libido and low sexual satisfaction. Half of the men were exposed to full spectrum light (to mimic sun exposure) for 30 minutes per day for 2 weeks. A placebo group was exposed to “sham” light for the same period. The men exposed to blue light showed a 3-fold improvement in subjective sexual function, along with a 70% increase in testosterone from baseline. (R) Shwing!
3. It reduces stress hormones.
Cortisol is the body’s chief waking hormone, but it also can become chronically elevated due to stress. Chronically-elevated cortisol is no bueno—it can cause the accumulation of inflammatory visceral fat (that’s the fat in your midsection that squeezes your organs), and shrink the memory center of your brain.
While finding appropriate means of dealing with stress (like meditation) is probably the best strategy, bright light exposure may help as well. When people were exposed to short wavelength (blue) light for 6.7 hours, their cortisol levels decreased by up to 25% compared to what they were at baseline. (R) Granted, spending 7 hours in daylight may seem a bit impractical today, but as hunter-gatherers, spending the whole day outside would be the norm. In fact, you could argue based on this research that spending the whole day indoors actually boosts cortisol 25%!
4. It makes you happier.
Serotonin, the neurotransmitter famous for its role in mood, is normally produced during the day, and darkness causes it to become converted to melatonin (this is why melatonin production is disrupted by bright light exposure at night). When scientists looked into the brains of people who’d died during both the summer and winter months, brain serotonin levels were higher in those who died in summer than in those who died in winter. (R) This may be why so many people are affected by Seasonal Affective Disorder, a dip in mood accompanying the shorter days of winter.
