OPSIN is intended to help you track and build healthy daily habits around sunlight and light exposure. It is not intended to diagnose, cure, mitigate, treat, or prevent any disease or health condition, and it is not a substitute for professional medical judgment, a laboratory test, or a calibrated instrument. OPSIN has not been evaluated or cleared by the U.S. Food and Drug Administration or any other regulatory authority as a medical device.
All values in OPSIN — including vitamin D (in IU), UV dose, illuminance (lux), color temperature, "safe" or "burn" times, and all scores — are modeled estimates derived from public forecasts, your self-reported profile, and published scientific models. They are not direct measurements of your body, your skin, or your actual vitamin D level. Individual responses to sun and light vary widely (commonly ±30–50% or more). Do not rely on OPSIN for any decision where precision matters.
This includes the estimated blood vitamin D level (25-hydroxyvitamin D): it is a mathematical model of what your level might be, not a blood test. Even after you calibrate it with real lab results, the value between tests is an estimate. Only a blood test ordered and interpreted by a clinician can establish your actual vitamin D status.
The OPSIN Coach is an automated wellness assistant, not a clinician. It provides general educational information about light, circadian rhythm, vitamin D, and sun safety based on your tracked data. It does not diagnose, does not prescribe or treat, and its responses are not medical advice. Do not act on coach output for any medical decision without consulting a qualified professional.
Most of this website is not the tracker. The science library — including the long review of light, vitamin D and human health and the short guides — is an evidence synthesis compiled from primary published sources. Every substantive claim is cited to the study, journal or research group that reports it, and carries an evidence grade so you can tell settled biology from a single unreplicated study. It is written to inform, not to instruct.
It is not clinical guidance, and it is not personalised to you. It is not written or reviewed by a clinician, it does not know your history, medications, skin type, lab results or risk factors, and it is not a substitute for someone who does. Where the science is contested — optimal blood levels and sun-exposure guidance both are — we present the competing positions rather than picking one for you. Nothing in it should be read as a recommendation to start, stop or change any treatment, supplement or sun-exposure habit.
The sunlight estimator on our home page is subject to everything in §2 above: it is a clear-sky mathematical model, not a measurement. It knows nothing about you beyond the values you type, ignores cloud, ozone, altitude and reflected UV, and individual synthesis varies widely. Treat its minutes as an illustration of how the variables interact — not as a dose.
We publish this research because we found it useful and think others will too. We have no commercial interest in any conclusion in it: we sell no supplements, lamps, devices or tests. That independence is a reason to trust the framing — it is not a reason to substitute it for medical care.
Always seek the advice of your physician or another qualified health provider with any questions about your vitamin D status, sun exposure, skin health, sleep, supplements, or any medical condition. Never disregard professional medical advice or delay seeking it because of something you read or saw in OPSIN. If you think you may have a medical emergency, contact your doctor or emergency services immediately.
Ultraviolet (UV) radiation from the sun can cause sunburn, premature skin aging, eye damage, and skin cancer, including melanoma. OPSIN's burn-time and safe-exposure estimates cannot account for everything that affects your real risk — such as reflected UV from snow, water or sand, sunscreen application and reapplication, sweat, medications that increase photosensitivity, or your individual skin. Use standard sun-protection practices and your own judgment. If you have a personal or family history of skin cancer, photosensitivity, or any condition affected by sun exposure, follow your doctor's guidance rather than an app.
OPSIN lets you log vitamin D supplements so your totals reflect your intake. It does not recommend, prescribe, or endorse any dose, brand, or product. Excessive vitamin D intake can be harmful. Talk to a healthcare professional before starting, changing, or stopping any supplement.
Using OPSIN does not create a doctor–patient or any other professional relationship between you and OPSIN or its creators.
By using OPSIN you acknowledge that you have read and understood this disclaimer and agree to use the app accordingly.