If you think life always feels just a little bit easier in the spring and summer, you’re onto something.
Natural light from the sun offers a range of physical, mental and behavioral benefits — which is why having even just an extra hour each day to soak it up may feel so monumental. Even on overcast days, the intensity of daylight — which hovers between 10,000 and 100,000 lux — is far greater than that of the artificial lighting in your home, school or office, which ranges from 100 to 500 lux.
Of course, the health risks of too much sunlight are well-known and include skin cancer, immune system suppression, and vision-damaging eye conditions like cataracts and macular degeneration. The key is to get some natural light exposure, while making sure not to overdo it.
Below are five ways natural light may boost well-being, and how to seek it out — safely — all year long.
It helps set your internal clock, which regulates most systems in the body.
Light regulates your circadian rhythm, or the biological clock that governs a host of bodily functions, including sleep, appetite and digestion, immunity, cardiovascular function, muscular function, and hormone production. Without light, your clock can become dysregulated, causing you to feel off — almost as if you’re jet-lagged, said Jamie Zeitzer, co-director of the Stanford Center for Sleep and Circadian Sciences.
Natural light exposure in the morning and at the same time every day can help keep things running smoothly, said Zeitzer. Experts suggest that getting 10 to 20 minutes of daylight soon after waking can help keep your clock on track, but as little as five minutes will help.
That’s because daylight inhibits the production of melatonin — the sleep hormone — and tells your brain it’s time to be awake, said Alon Avidan, a neurologist and the director of the UCLA Sleep Disorders Center. At the same time, production of other wakefulness-promoting brain chemicals — histamine and cortisol — ramps up. All of this translates to you feeling alert and energized during the day, and your body operating as it should.
It might make it easier to fall — and stay — asleep at night.
Getting your body clock on track in the morning sets you up for proper melatonin production all day long — including making sure your body releases more of it at the right time at night, when it’s time to wind down for sleep. People often feel tired roughly 15 hours after seeing morning light, Zeitzer said.
Research suggests that daytime light may not only enhance sleep onset at night but could also improve sleep quality, extend sleep duration and prevent nighttime waking. Stepping outside before 10 a.m. is an effective way to establish a bedtime and improve your sleep, a recent study found.
Another benefit: Getting more light during the day may help offset the negative effects of artificial light (like the glow from your smartphone) at night, Zeitzer said. Research has linked this type of light exposure to delayed sleep onset and even negative effects on mood and blood pressure. Spending time outside any time of day may help prevent those consequences, but studies suggest a half-hour in the late afternoon, around 4 p.m., may be most effective at countering these effects, said Zeitzer.
If you do shift work or keep unconventional hours for other reasons, experts recommend changing when you expose yourself to light. For example, if you work from 7 p.m. to 7 a.m., aim to get an hour of bright light in the evening, and try to limit the amount of light you’re exposed to in the morning when you leave work, as this could prevent you from being able to sleep during the daytime, said Zeitzer.
It may improve your blood sugar.
Light exposure influences many metabolic processes, including insulin secretion and glycolysis — the breakdown of glucose in food to be used in the body. Without it, the circadian rhythm can become disrupted, impairing insulin function and affecting blood sugar levels. Over time, this can contribute to the development of metabolic disorders such as Type 2 diabetes and obesity, said Tobias Eckle, a professor of anesthesiology at the University of Colorado Anschutz who researches the health effects of daylight exposure.
Some research suggests that bright light exposure may improve glucose control in people with Type 2 diabetes. In a small new study, researchers split 13 people with Type 2 diabetes into two groups: some who sat near a window while working in an office for 4½ days, and others who worked under artificial lighting. The researchers tracked their blood sugar levels with continuous glucose monitors and discovered that, compared with the artificial-lighting group, those positioned near windows spent more time in a healthy blood sugar range.
It’s a small study and doesn’t prove cause and effect, but it is interesting, particularly if further research confirms the benefit. If you spend most of your time indoors, Eckle suggested trying to step outside or sit near a window for, ideally, at least 30 minutes. If you can’t, even a few minutes of daylight on your way into the office may be enough to improve glucose levels: A 2021 study found that those who got 10 minutes of morning daylight over the course of seven days experienced improvements in their blood glucose levels compared with people who did not get morning light.
It could be an instant mood-booster.
Sunlight can be a powerful mood enhancer, according to Zeitzer, and the effect may be immediate for many people. “You go outside and you feel better,” he said.
More consistent natural light exposure has been linked to better moods, too. For example, many people experience the blues during the winter but feel better in springtime. (Although summer seasonal depression can happen too, it’s not as common.)
The reason natural light can be such a mood-booster is less clear, but scientists suspect that it helps regulate the release of serotonin and dopamine, Avidan said. Longer daylight hours result in higher serotonin levels, which “helps improve emotional stability,” he said. In fact, this is why light is increasingly used as a treatment for depression, including bipolar depression, perinatal depression and seasonal depression.
Additionally, the outdoors — specifically, the air, sounds and movement — stimulates your brain in a way that may make you feel happier, added Zeitzer, compounding the feel-good effects of light itself.
It encourages healthy levels of vitamin D.
Vitamin D is a nutrient that plays an important role in a variety of bodily functions, including bone health, muscle density, nerve activity and immunity. Evidence also suggests that vitamin D offers protection against chronic diseases like cancer, dementia and Type 2 diabetes. It’s especially important for children, who can develop weak-bone conditions, like rickets, without it.
There are three ways to increase your vitamin D levels: eating foods rich in the vitamin — including fatty fish, cheese and fortified products like milk — taking supplements, or exposing your skin to sunlight.
“Sun exposure is very important for the metabolism of vitamin D,” said Avidan. In fact, it’s the most efficient way to boost levels.
For optimal vitamin D levels, aim for 5 to 30 minutes of sun daily, or at the very least twice a week.
A few safety tips to keep in mind
Seeing as heavy sun exposure increases your risk of skin aging and skin cancer, as well as other health issues, it’s worth taking extra precautions when outside.
In general, ultraviolet (UV) rays are strongest between 10 a.m. and 4 p.m., so if you plan on being outdoors midday, consider slathering on sunscreen with an SPF of 15 or higher that is broad spectrum, meaning it blocks both UVA and UVB rays. According to Eckle, sunscreen won’t inhibit the effects of natural light on circadian rhythms. You can also opt for protective clothing such as wide-brimmed hats, long pants and long-sleeved tops.
To reap the full health benefits, light does need to pass through your retinas, Eckle said. While sunglasses may inhibit some of the above-mentioned effects, most eye experts strongly recommend that you wear sunglasses that block UVA and UVB rays to prevent vision-damaging conditions. Even with sunglasses, you’ll still be exposed to many more lux of light than you would be indoors, added Zeitzer.
Finally, you can always find light through other sources. Light filtered through windows, though less potent than direct sunlight, can still boost your well-being while blocking UV radiation, said Zeitzer, as can sitting in front of a lightbox that emits 10,000 lux for 30 minutes. “Many of the biological effects of natural light can be reproduced by artificial lighting,” he said.
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