Press release
Wavelength measures the light that sets your body clock
8 July 2026
Impulse Arc has released Wavelength, an iPhone app that reads the light you are actually sitting in and tells you whether it is helping or hurting your sleep. Point the camera at the room; Wavelength measures the melanopic light, the part of the spectrum the body clock responds to, and turns your readings into a plan.
Light-meter apps give you a number and leave you with it. Sleep apps give you a plan built from what you typed in. Wavelength is the only one that does both: it measures your real light and coaches your real schedule, with no wearable — just the camera already in your pocket.
What it answers
When to get bright light and when to avoid it, so a drifting sleep schedule settles. The moment in the evening when the light around you starts keeping you up. How to move sleep to fit a run of shifts and stay alert through the night. And, set a destination, when to chase daylight and when to hide from it, before and after a flight, so you land closer to local time.
A notification as each window opens, so a walk, a workout or a wind-down can be planned around it.
Where the numbers come from
Wavelength follows the expert-consensus light recommendations of Brown et al. (2022, PLOS Biology) and the light response curves of Hannay et al. (2019, Journal of Biological Rhythms) and others. Research links well-timed light to steadier mood, sharper focus and more energy. The app supports sleep and circadian alignment; it does not diagnose or treat any medical condition.
Camera readings are approximate rather than lab-grade, which is the right precision for the question being asked: is this light helping or hurting my sleep right now.
Availability
Wavelength is on the App Store for iPhone. The live light meter is free; a seven-day trial unlocks the coaching, then $29.99 a year.
About Impulse Arc
Impulse Arc LLC is a California studio building small, carefully made products, each meant to do one thing well: Wavelength; Continuo.fm, lossless sharing for musicians' mixes and masters; and Absurdly Optimized, rigorous reviews and calculators. It is run by Ben Kazez, a concert singer who earlier created FlightTrack and founded Mobiata, acquired by Expedia in 2010.