Sun Sessions — Track Your Photobiology

Sun isn't just vitamin D. Different parts of sunlight do different things — set your body clock, support circulation, charge your mitochondria, regulate mood-hormones. The ☀ Light & Sun lens tracks your light exposure across six biological channels and lets you correlate them with your labs and wearable data over time.

Six channels, one biology

Channel	What it does	Spectrum
Vitamin D	UVB on bare skin makes vitamin D. Stops increasing around the point your skin starts to redden — longer is not better.	UVB 290–315 nm
Mood & hormones	Sun on skin triggers a hormone cascade — α-MSH (the tan signal), β-endorphin (mood), ACTH (stress response). Part of why sun feels good.	UVB + UVA
Cardiovascular	UVA from skin releases nitric oxide — supports blood-vessel function, lowers blood pressure, improves circulation, dampens inflammation.	UVA 315–400 nm
Outdoor eye light	Outdoor 360–400 nm hits sensors in eye and skin. Linked to eye health and dopamine release — the difference between "outside" and "window light" even when both feel bright.	Violet 360–400 nm
Body clock	Bright light at the eye sets your circadian rhythm — earlier bedtime, faster wake-up, deeper sleep. Strongest effect in the first 2 hours after sunrise.	Blue ~490 nm (melanopic peak)
Cellular repair	Solar 600–1400 nm penetrates deep into tissue and reaches mitochondria. Supports recovery, raises local melatonin in cells, reduces inflammation. The half of sunlight that windows block.	Red + IR-A 600–1400 nm

Each channel is qualitative — none / low / moderate / good / strong — based on how your accumulated dose compares to a literature-rough target. The dashboard "Light Today" strip scores against the daily target; the "Your light, by what it does" section scores the 7-day rollup against a 7×daily target so a weekly view doesn't get unfairly downgraded. We deliberately don't show raw numbers; the AI sees them but you don't have to.

Logging a session

One-tap quick log is the primary flow:

1. Going outside? Tap ☀ Log a sun session (on the Light Today strip or the Light & Sun page).
2. Coming back inside? Tap the same button — now labelled "⏹ Stop session — N min".

That's it. The app pulls the actual UV index and ozone for your location, reconstructs the spectrum at your zenith angle, and computes your per-channel doses on the spot.

Quick-log defaults are inherited from your last session. Want different exposure or eyewear? See "Adjust before starting" below.

Going for a 30-second setup first

When you open the Light & Sun page for the first time, an onboarding card asks four quick questions plus an optional 10-question malillumination baseline:

• Skin type (Fitzpatrick I–VI) — used to scale your personal sunburn threshold
• Home lighting — LED cool, LED warm, fluorescent, incandescent, mixed
• Eyewear outside — none, sunglasses, clear glasses, both, contacts-with-UV-block
• Location precision — your country (from profile) is the default; tap "Use precise location" for sharper UV math (one-time)
• Photosensitizing medication checkbox — if you take tetracyclines, isotretinoin, amiodarone, thiazides, NSAIDs, St. John's Wort, or similar, your burn threshold drops ~2.5×
• Light-burden audit (optional, 10 yes/no questions) — captures how indoor / glass-mediated / artificial-light-dominated your modern life is

Answers stay on your device. The AI uses them as a baseline ("your low body-clock channel makes sense given your light-burden score of 8/10").

Burn-risk safety

The Light Today strip and the Light & Sun page show today's burn risk in plain English:

• Safe — under 30% of your skin's daily threshold
• Moderate — 30–70%
• Approaching — 70–100% (cover up if you go back out)
• Reached — over 100% (sunburn risk, no more direct sun today)

This is computed from each session's CIE-erythemal-weighted dose vs your Fitzpatrick threshold. We never recommend sun-gazing — direct retinal UV is tracked separately as a safety counter.

Light therapy devices

Got a red-light therapy panel, a SAD lamp, a UVB lamp, a dawn simulator, or a full-spectrum bulb? Add it from the My light devices section on the Light & Sun page. We ship a 19-preset library (Chroma, EMR-Tek, Mitochondriak). For other brands (Joovv, Mito Red, Sperti, Verilux, Lumie, etc.) paste the spec sheet into the custom-device dialog and the AI extractor maps wavelength + irradiance into the same schema.

Therapy device sessions feed the same per-channel dose totals as outdoor sun. A user with no outdoor time but a daily PBM routine still sees the Cellular repair channel light up — and the AI sees them too (the always-tier prompt now includes device-only users, and the rolling correlation engine includes the two PBM channels (660 nm red / 810-850 nm NIR) so device-heavy users get device × biomarker correlations surfaced).

Light environment

Most users spend 8–14 hours/day under indoor lights. The Light environment section maps your rooms (LED type, hours/day, after-sunset use) and your screens (device, hours/day, evening use, blue-blocker). Indoor light is the dominant exposure for many; tracking it lets the AI see your full day.

Light tools (on-device)

Eight measurement utilities, all running fully in your browser:

• 📏 Lux Meter — uses your phone's ambient-light sensor when available, camera-based estimate otherwise
• ⚡ Flicker Detector — your camera at 240 fps catches LED PWM banding; we compute a 0–3 risk score
• 🎨 Color Temp — tells you your indoor CCT and whether it matches the solar time
• 🔬 What is this light? — classifies the source as fluorescent / cool LED / warm LED / incandescent / daylight
• 🪟 Glass Transmission — measure inside and outside, see how much your window blocks
• 🌙 Sleep Darkness — long-exposure read at the pillow, tells you if the bedroom is dark enough for full melatonin
• 🌅 Golden hour log — one-tap session entry for sunrise / sunset
• 👁 Eye-level audit — continuous capture as you walk through your home; one tap per room populates the entire Light Environment

Camera frames never leave your device.

Where the data flows

• AI chat — every chat carries a Light & Sun summary: your active deficits, your devices, your week's per-channel exposure (sun + devices combined), and your skin's daily sunburn budget. Once you have ≥4 weeks of overlapping sessions and labs, channel-by-biomarker correlations join the standard tier.
• Detail-modal overlays (in development) — toggle a sun-channel layer on biomarker detail charts to see the dose-vs-marker relationship visually.
• Wearables strip — sun and wearables sit side-by-side on the dashboard; the AI sees both.
• Genetics — your DNA-aware AI prompts already factor in VDR, MC1R, CYP2R1, GC, NPAS2, CRY2, PER3 polymorphisms when relevant.

Privacy posture

• Lat/lon defaults to your country from your profile — no automatic geolocation prompt at session start
• Optional one-time precise-location upgrade is stored locally in this device's profile; never synced
• UV/ozone data — pick your Sun data source on the Light & Sun page itself. Four options:
  • Default — CAMS atmospheric forecast (real KNMI-validated total column ozone + AOD + PM₂.₅/PM₁₀) merged with Open-Meteo for clouds, temperature, and a baseline UVI
  • Open-Meteo only — skip CAMS entirely; one fewer upstream sees your lat/lon
  • Self-hosted — run your own getbased-uvdata server (the CAMS relay code is open source) and point the app at it; lat/lon never leaves your infrastructure
  • Manual / UV meter — type the UV index per session; no network calls at all
• Source confidence is computed per request: snapshot age, cloud cover, sun elevation, UVI band, and stale flag all discount the displayed percentage. A reading at low sun under heavy cloud honestly drops to ~40%, even from CAMS — no false precision
• All measurements (lux, flicker, CCT, etc.) live in importedData.lightMeasurements on this device
• Camera frames and sensor readings are processed in-browser and discarded — they never reach a server

Honest caveats

• Channel doses are proxies, not measurements. We integrate published action spectra (CIE 174:2006 previtamin-D3, CIE S 007 / ISO 17166 erythemal (McKinlay-Diffey 1987), CIE S 026:2018 melanopic, cytochrome-c-oxidase bands from Karu/Hamblin, etc.) over a clear-sky-reconstructed solar spectrum (Bird-Riordan 1986). Real-world variance is ±25% relative.
• Lux meter is calibrated approximately. AmbientLightSensor readings are accurate; camera-based readings have a one-time calibration multiplier in localStorage and label themselves as "estimate" in AI confidence.
• Burn-risk model is conservative and uses a 1.5× hard cap with explicit override warnings. We never recommend exceeding your personal threshold.
• No medical advice. This is measurement, not prescription. Consult a healthcare professional for any concern.

In-session controls

When a session is running, the Light & Sun page pins a Live card at the top with these controls:

• ⏸ Pause — freezes dose accrual during a shade break (timer keeps ticking; toggle to resume)
• 🔄 Flip — tap when you turn over front↔back. The region picker is anatomically scoped to a single side at a time (selecting every region is ~50% of total skin since front + back are exclusive); flipping doubles the vit-D yield to acknowledge that fresh skin keeps synthesizing after the first side approaches saturation. Same convention dminder uses for "both sides over the session"
• 🧴 Sunscreen — log a mid-session reapplication; commits the slice computed under the OLD SPF, then continues with the new value
• 🛰 Ozone — manual override of the total-column DU figure if you have a meter or local advisory

Detailed sessions also support a per-region silhouette picker — toggle individual anatomical regions for targeted-UV protocols (face only, abdomen only, etc.).

What's coming

• Spectral overlay on biomarker charts — see channel × marker visually, not just in chat
• Phase-2 air-quality fields from CAMS — NO₂ / SO₂ / CO / surface ozone via the regional CAMS-Europe dataset (currently sourced from Open-Meteo's AQI endpoint, which already wraps CAMS for these)