Who makes it
DaySight is made by Steven Hylands, an independent builder who wanted a simple way to see when the light comes and goes, and to get outside at the right times. It is free to use, with no account and no ads.
Why light timing matters
Your body runs on a roughly 24-hour clock, and light is the main signal that keeps it in time. The NIH's National Institute of General Medical Sciences names light and dark as the biggest influence on these circadian rhythms.
When you get the light matters. CDC training material from NIOSH explains that bright morning light moves the clock earlier, so you get sleepy and wake earlier, while bright evening light moves it later. That is why DaySight puts the hours after first light first.
Outdoor light is far brighter than indoor light, even on a cloudy day, which is why DaySight counts time outside rather than time near a window.
DaySight is general information, not medical advice. If you have trouble sleeping, or work shifts, talk to a doctor.
Where the numbers come from
Every time is calculated from the sun's position for the place you're looking at. Solstice times come from the US Naval Observatory, and cloud cover from Open-Meteo. The method, and its limits, are on how DaySight calculates.
Contact
Spotted a wrong time, or have an idea? Email hello@daysight.app. Corrections are fixed and the page's "Updated" date changes when they are. How DaySight handles your data is on the privacy page.