Clear, cited guides to using light well. Honest about what's established and what isn't.
OPSIN is a wellness tracker, not a medical device. These guides are educational, not medical advice —
for your own situation, talk to a clinician and get a blood test.
The single most reliable thing light does for you: anchoring your body clock so you
fall asleep and wake more easily. What the evidence says, and how to do it.
Above a certain latitude, the winter sun physically can't make vitamin D — no matter
how long you stay out. Here's why, and what to do instead.
Want this applied to your day and place? OPSIN turns the science below into a live plan —
the best windows to go outside today, how long is safe for your skin, and your vitamin D balance.
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