I built a daily sunlight tracker
I kept trying to explain how important outdoor light is and how most people aren’t getting enough. Eventually I figured that showing is more effective than telling. So we built a free app that uses your Apple Watch or iPhone to automatically track your light exposure throughout the day. It tells you if you’re getting enough, shows you how consistent you are, and rewards habits that support hormone balance. It's in beta on TestFlight, let me know what you think!
I built a daily sunlight tracker launched on June 26, 2025 with 46 votes, #563 of 7,999 launches that month and more than 90% of that year's launches. The site was still online in September 2026, 1 year on.
In plain words
This app tracks daily sunlight exposure using Apple Watch or iPhone sensors to measure how much outdoor light users receive throughout the day. It provides feedback on whether exposure meets recommended levels, displays consistency patterns, and offers rewards for habits that support hormone balance. The free tool targets people concerned about light's effect on their health and circadian rhythms. Currently available as a beta on TestFlight.
written from the facts on this page · September 2026
From the sources
The Lume app makes tracking your sunlight effortless. By aligning your daily light exposure with your body’s biological rhythm, it helps lift mood, boost energy, and improve sleep quality.
Discover Lume Health: the wearable that measures cortisol & circadian rhythms, giving you real-time insights for better sleep, energy & stress.
We are building the world’s first wearable hormone monitoring platform, starting with cortisol and circadian health. Experience the future of hormone health with our wearable that continuously monitors your hormones. By analyzing your sweat, Lume unlocks real-time insights into your Circadian Health to optimize your habits and align to your body’s natural rhythms. Experience the future of hormone health with our wearable that continuously monitors your hormones. By analyzing your sweat, Lume unlocks real-time insights into your Circadian Health to optimize your habits and align your body’s natural rhythms. We’re launching soon. Get on the list to be the first to know. With so much time…from lumehealth.io
Does a similar job
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Hey HN, after the app I actually used to track my period wanted me to log in and save my data in the cloud, I decided to write my own. Most apps in this area are based on a subscription model and display far too much information anyway. For me, a simple calendar is enough where I can add a few notes if necessary. So that is the result of my work - a simple design and the data is only saved on the smartphone.
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