How Sunlight Benefits Your Brain

The next time you’re hit with a post-lunch energy slump, take a brief walk outside. If that’s not an option, plop yourself next to the sunniest window you can find.

Why? Daylight is a major source of blue wavelengths of light, which research has shown can boost your alertness, concentration and even your mood. “Light is like a cup of coffee,” says Mariana G. Figueiro, director of the Light and Health Research Center at Mount Sinai.

MEMBERS ONLY

How does daylight perk you up? It triggers your body’s circadian rhythm — the internal “clock” in your brain. In response to light, your circadian clock signals you to be more alert. Later, when the sun goes down, your circadian clock promotes sleep. 

“It’s almost like a switch,” Figueiro says. Many brain chemicals are involved in this complex interplay. For example, light kicks off production of serotonin, known as a “feel-good” hormone because it contributes to positive emotions and behavior. Later, darkness cues production of melatonin, a hormone that makes us drowsy.

That dose of sunlight will make you feel more alert, and you may also have a sunnier outlook. People who got the most natural light during the day were happier and less likely to have symptoms of depression than those who got the least, according to a study of 502,000 adults between the ages of 37 and 73, published in the Journal of Affective Disorders in 2021. 

Exposure to daylight may support your memory and thinking skills, too. One study, published in Scientific Reports in 2022, analyzed cognitive testing data from 1,838 adults, average age 42. The researchers also reviewed several years’ worth of solar radiation data based on participants’ zip codes and found that people living in the sunniest areas for two to five years before the cognitive tests had better scores than those who got the least daylight.