Have you noticed that time outside makes you feel better? Studies show sunlight has powerful effects on your mood, immunity, metabolic function, and libido. I spent some time reviewing studies with hundreds of thousands of participants, including breakthrough discoveries published in 2025, and the results raise questions about the long-held advice to avoid the sun at all costs.
#1. Our immune cells have built-in alarm clocks that run on daylight
White blood cells that fight off infections are significantly more effective when exposed to daylight. But when deprived, their effectiveness plummets. The immune system is designed to be most active during daylight hours. Yet here we are, spending 90% of our time indoors—pop out for a few minutes several times a day if you can, particularly in the morning.
#2. Sunlight improves mood
A study found that spending a single sunny day at a baseball game was 1,000 times more effective at boosting mood than taking prescription antidepressants. Researchers studying hospitalized patients with bipolar depression found that those got morning sunlight were discharged earlier.
Why? Sunlight triggers serotonin production in your brain and skin. Even blind people show increased serotonin levels when their skin is exposed to UVA light.
#3. Sunlight can lower breast cancer risk
Women with higher solar UVB exposure have half the incidence of breast cancer compared to those with lower exposure. Women who got more sun exposure between ages 10–19 had a 35% lower risk of developing breast cancer later in life.
#4 Lower diabetes and obesity risk
Studies found that sunlight exposure—not vitamin D supplements or blood levels—reduced the risk of obesity and type 2 diabetes. In mice studies, UV light prevented weight gain on a high-fat diet, while vitamin D supplements had zero effect.
#5 Lower multiple sclerosis risk
People with low sun exposure had 2.2 times higher risk of MS than those with high exposure—even after adjusting for vitamin D levels. The UV radiation was suppressing the disease through mechanisms that have nothing to do with vitamin D.
#6 Blood pressure modulator
Your skin stores massive amounts of nitric oxide, which is released when you’exposed to UV light. This helps relax your blood vessels and naturally lowers blood pressure. Just 30 minutes of midday sun exposure significantly increases nitric oxide release and improves blood vessel function.
#7 Enhanced libido
Human studies found that sunlight exposure positively correlates with increased testosterone levels in men. Both men and women report enhanced romantic passion after sunlight or UVB exposure.
#8 A longer life
A UK study that followed almost half a million people for more than a decade found that people who actively sought out sun exposure had:
- 14% lower risk of death from any cause
- 19% lower risk of death from heart disease
- 14% lower risk of death from cancer
How to safely harness the sun’s healing powers
This isn’t about ignoring the risks of overexposure. It’s about working WITH your biology instead of against it with these strategies:
- Optimal timing: Morning exposure for maximum benefit. Your circadian rhythms, immune function, and mood regulation all depend on that morning light hitting your skin and eyes.
- Duration: 15-30 minutes daily, depending on your skin type and the UV index. Start conservatively and build up.
- What to watch for: The balance between benefit and oxidative stress. You want enough exposure to activate all these beneficial pathways without causing DNA damage.
Start your sun protocol tomorrow
Try 15 minutes of morning sun, without sunscreen or sunglasses, for seven days (please do not look directly AT the sun!).
Pay attention to your mood, energy, and sleep quality. I’ve had lots of patients report significant improvements in these areas with increased exposure to sunlight (but not too much, this is not a license to burn.)
I hope this helps you appreciate nature’s most powerful, diverse, and unmonetized supplement this summer!
(While sunlight has plenty of health benefits independent of vitamin D, most people still need to supplement vitamin D. I recommend therapeutic doses of Vitamin D3+K2 from Just Ingredients.)
Quick References:
- Immune system runs on daylight: DOI: 10.1126/sciimmunol.adn3080
- Baseball game beats antidepressants 1000x: https://buff.ly/iR5d7zx
- Sun exposure reduces death risk 14-19%: DOI: 10.1016/j.healthplace.2024.103328
- Sunlight boosts testosterone/libido: DOI: 10.1016/j.celrep.2021.109579
- Morning sun reduces hospital stay: DOI: 10.1016/s0165-0327(00)00149-x