> ## Documentation Index
> Fetch the complete documentation index at: https://docs.getbased.health/llms.txt
> Use this file to discover all available pages before exploring further.
# Log sun exposure sessions in getbased
> Track vitamin D, circadian rhythm, cardiovascular, and four other biological channels from every sun session — with live dose totals and burn alerts.
Sun isn't just vitamin D. Different wavelengths do different things — set your body clock, support circulation, charge your mitochondria, regulate mood hormones. The **Light** lens tracks your sun exposure across six biological channels and lets you correlate them with your labs and wearable data over time.
## What sun sessions tracks
Each session is scored across six channels based on how your accumulated dose compares to a literature-derived daily target. Scores run from **none → low → moderate → good → strong**.
| Channel | What it does | Spectrum |
| --------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------ |
| **Vitamin D** | UVB on bare skin triggers vitamin D synthesis. Synthesis plateaus before your skin reddens — more time does not mean more vitamin D. | UVB 290–315 nm |
| **Mood & hormones** | Sunlight on skin triggers α-MSH (the tan signal), β-endorphin (mood lift), and ACTH (stress response). | UVB + UVA |
| **Cardiovascular** | UVA releases nitric oxide from skin — supporting blood-vessel function, lowering blood pressure, and dampening inflammation. | UVA 315–400 nm |
| **Outdoor eye light** | Violet light at 360–400 nm reaches sensors in both the eye and skin. Linked to eye health and dopamine. This is what distinguishes real outdoor light from window light, even when both feel equally bright. | Violet 360–400 nm |
| **Body clock** | Bright light at the eye anchors your circadian rhythm — earlier bedtimes, faster wake-up, deeper sleep. Strongest in the first two hours after sunrise. | Blue \~490 nm (melanopic peak) |
| **Cellular repair** | Solar 600–1400 nm penetrates deep into tissue and supports mitochondria, local melatonin production, and recovery. This is the half of sunlight that windows block entirely. | Red + IR-A 600–1400 nm |
The app deliberately doesn't surface raw dose numbers. The AI sees them, but your dashboard shows qualitative scores — which is all you need to make decisions.
## How to log a session
The primary flow is a one-tap quick log.
Tap **Log a sun session** in the Light lens or the **Light Today** dashboard widget. The app pulls the current UV index and ozone for your location, reconstructs the spectrum at your sun angle, and starts accruing dose.
When you come back inside, tap the same button — now labelled **Stop session — N min**. That's the whole flow.
Quick-log defaults carry over from your last session. If you want to adjust body regions, eyewear, or SPF before you start, open the full session picker from the Light lens.
### First-time setup
The first time you open the Light lens, a short setup card asks a few questions to calibrate your personal scores:
* **Skin type** (Fitzpatrick I–VI) — used to scale your personal sunburn threshold
* **Home lighting** — LED cool, LED warm, fluorescent, incandescent, or mixed
* **Eyewear outside** — none, sunglasses, clear glasses, or contacts with UV block
* **Location precision** — your country is the default; tap **Use precise location** for sharper UV math (stored on this device only, never synced)
* **Photosensitizing medication** — if you take tetracyclines, isotretinoin, thiazides, NSAIDs, amiodarone, St. John's Wort, or similar drugs, your effective burn threshold drops roughly 2.5×
An optional 10-question light-burden audit captures how indoor- or artificial-light-dominated your typical day is. The AI uses this baseline when interpreting your channel scores ("your low body-clock channel makes sense given your light-burden score").
## Live session controls
While a session is running, a **Live** card pins to the top of the Light lens with running dose totals per channel. You can interact mid-session:
| Control | What it does |
| ------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Pause** | Freezes dose accrual during a shade break. The timer keeps ticking. Tap again to resume. |
| **Flip** | Tap when you turn from front to back (or vice versa). The region picker covers one side at a time; flipping tells the app fresh skin is now exposed, which doubles the vitamin D yield to reflect that newly-exposed skin keeps synthesizing after the first side approaches saturation. |
| **Sunscreen** | Log a mid-session reapplication. The app commits the dose accrued under the previous SPF, then continues under the new value. |
| **Ozone override** | Manually enter total-column ozone in Dobson Units if you have a local advisory or a personal meter. |
For targeted protocols (face only, abdomen only, back only), the detailed session view includes a **per-region anatomical silhouette picker** covering 16 regions split across front and back.
## MED calculation and burn alerts
The Light lens and **Light Today** dashboard widget show your **burn risk** in plain English throughout the day:
* **Safe** — under 30% of your personal daily sunburn threshold
* **Moderate** — 30–70%
* **Approaching** — 70–100% — time to cover up if you go back outside
* **Reached** — over 100% — sunburn risk, no more direct sun today
These thresholds are computed from each session's CIE-erythemal-weighted dose compared to your Fitzpatrick skin type's minimal erythemal dose (MED). The burn model uses a 1.5× conservative cap and warns you explicitly before you reach it.
If you've checked the photosensitizing medication box in your setup, your effective burn threshold is reduced by approximately 2.5×. Alerts will fire sooner.
## Atmosphere data
getbased uses real atmospheric data to reconstruct the solar spectrum at your location and elevation. You can choose your **Sun data source** directly in the Light lens:
KNMI-validated total column ozone, aerosol optical depth, and particulate data from the Copernicus Atmosphere Monitoring Service (CAMS), merged with Open-Meteo for cloud cover, temperature, and a baseline UV index. Best accuracy when you need precise channel estimates.
Skips CAMS entirely. One fewer upstream service sees your location. Slightly less precise ozone data.
Run your own `getbased-uvdata` server (the CAMS relay code is open source) and point the app at it. Your latitude and longitude never leave your infrastructure.
Type the UV index yourself before each session. No network calls at all.
**Source confidence** is computed per request — snapshot age, cloud cover, sun elevation, UV index band, and a stale flag all discount the displayed percentage. A reading at low sun under heavy cloud honestly drops to around 40%, even from CAMS. No false precision.
Latitude and longitude default to your country from your profile. No automatic geolocation prompt fires at session start. The optional precise-location upgrade is stored on this device only and never synced.
## Photobiology device library
Got a red-light therapy panel, a SAD lamp, a UVB lamp, or a full-spectrum bulb? Add it from the **Light Devices** section in the Light lens.
getbased ships a **19-preset library** covering devices from Chroma, EMR-Tek, and Mitochondriak. For other brands — Joovv, Mito Red, Sperti, Verilux, Lumie, and others — paste the spec sheet into the custom-device dialog and the AI extractor maps wavelength and irradiance into the same schema.
Device sessions feed the same six per-channel dose totals as outdoor sun. If you use a photobiomodulation (PBM) panel but spend little time outdoors, the **Cellular repair** channel will still light up — and the AI will see your device sessions in context. The correlation engine also includes the two PBM-specific channels (660 nm red / 810–850 nm NIR) so device-heavy users get device × biomarker correlations surfaced over time.
## AI sun analysis
After each session, getbased can generate a verdict on your sun exposure. The AI evaluates your channel mix, your device use, your skin type, your photosensitive-medication flag, and your rolling weekly totals — and returns a green / yellow / red assessment with a short explanation.
Verdicts fire automatically when you stop a session. You can also request a fresh analysis manually from the session detail card.
## Where sun data appears in AI context
Every AI chat includes a Light summary in the always-on context tier, covering:
* Your active channel deficits and surpluses
* Your configured devices and recent device sessions
* Your week's per-channel exposure (sun and devices combined)
* Your skin's daily sunburn budget
Once you have four or more weeks of overlapping sessions and lab results, channel-by-biomarker correlations join the standard context — so the AI can reason about things like the relationship between your weekly UVB dose and your 25-OH vitamin D trend.
Sun and wearable data sit side-by-side in dashboard widgets and AI context. The AI sees both simultaneously, which lets it reason about things like "low HRV on days after high-UV sessions" without you having to connect the dots yourself.
If your DNA includes variants in VDR, MC1R, CYP2R1, GC, NPAS2, CRY2, or PER3, the AI prompts already factor those in when those genes are relevant to the question at hand.