The Study
Photo-induced nitric oxide modulation in human skin: Impacts of geographic location and seasonality on health and disease.
This article is like a story that puts together lots of other science papers to explain how sunlight might affect your skin. It doesn't do any new experiments, so we can't say sunlight definitely causes or fixes skin problems—just that it might be connected.
Analysis score
Maximum 5 for a narrative review.
Where the score came from
Sunlight releases a calming chemical called nitric oxide in your skin that fights harmful stress from the sun. When you don’t get enough sun (like in winter), this calming system breaks down, making skin diseases like eczema and psoriasis worse.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 51 / 100
Quality score
Based on clinical experience or non-systematic literature reviews. The lowest level of evidence as they are most susceptible to bias and personal perspective.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — less sun means less natural skin protection, which can make chronic skin rashes and inflammation worse for millions of people.
- 2No numbers or effect sizes reported.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of photochemistry and photobiology. B, Biology
Year
2025
Authors
P. E. da Costa, M. S. Baptista
Related Content
Claims (6)
When your skin is exposed to sunlight, it releases a substance that helps relax your blood vessels, which can lower your blood pressure.
When your skin is exposed to sunlight, it releases a natural substance called nitric oxide that helps calm down harmful molecules in your skin and keeps things balanced — but this doesn't work right if you have long-term skin inflammation.
When there's less sunlight in winter or far from the equator, your skin makes less nitric oxide from sunlight, which can upset the balance in your skin and make conditions like psoriasis or eczema worse.
In people with certain skin conditions like psoriasis and eczema, their bodies make too much of two harmful chemicals that combine to create a damaging substance, which throws off their natural balance and weakens their body’s ability to protect itself.
Some light-based treatments might help calm down angry, inflamed skin by copying how sunlight naturally balances certain chemicals in your skin, which could make conditions like eczema or psoriasis feel better.
Sunlight can create harmful molecules in your skin, but your body naturally produces nitric oxide to balance them out—this balance keeps your skin healthy.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.