Move a few inches back from a light source and the amount reaching your skin doesn't drop by a few inches worth. It drops fast and understanding why changes how you think about every red light session you do.
What Irradiance Actually Means
Irradiance is simply how much light energy lands on a given area of skin, usually measured in milliwatts per square centimeter(mw/cm²). Two people using the exact same RedRush panel can get very different exposure depending on nothing more than how far away from it they are. That's the entire idea behind irradiance, and it's why distance isn't a minor setup detail. It's the dial that controls your actual dose.
Light doesn't fade evenly as you move away from its source. It follows what physicists call the inverse square law: double the distance, and the light spreads out over four times the area, so the concentration hitting any single point drops off much faster than distance alone suggests. Step back a little, and you lose more intensity than it feels like you should.
This isn't specific to red light panels. It's the same reason a flashlight looks blinding an inch from your eye and barely noticeable across a room. The physics doesn't care what's producing the light.
Why RedRush Uses Three Distance Zones
This is exactly why RedRush panels are built around three set distances rather than one. Each trades intensity for coverage in a different way.
At 6 inches, the light concentrates on a small area of skin at a time. It's a setting for a specific, limited spot, not your whole body at once.
At 24 inches, the light spreads out enough to cover a meaningful portion of your body in each pass, which is why this distance works as the everyday starting point for full-body sessions. This is also where panel size matters. The 840 Pulse's larger array (280 LEDs) covers roughly twice the surface area per pass compared to the 400 Pulse (133 LEDs), which is the direct reason the 840 Pulse's front-and-back timing runs closer to 5 minutes per side at 24 inches, while the 400 Pulse's runs closer to 20 minutes split across four sections. Same distance, same dose logic, different panel size doing different amounts of work per pass.
At 36 inches, the light spreads further still, covering your entire body at once with less concentration in any one spot. This is the gentler, full-coverage option built for anyone who wants broad exposure without sitting close.
More Distance Doesn't Mean Weaker, It Means Different
It's tempting to assume that closer is always better because it feels more intense. But intensity and appropriateness aren't the same thing. Being 6 inches from the panel while trying to cover your entire body at once isn't practical, and it wasn't designed for that. The three zones exist because different goals call for different tradeoffs between concentration and coverage, not because one distance is objectively superior to the others.
A Practical Way to Think About Dose
You don't need a light meter to use a panel correctly. What matters more is consistency: picking a distance that matches what you're trying to do, using the timing paired with it, and sticking to that combination instead of guessing at a new setup every session. RedRush panels come with these distance-and-time pairings built into the manual specifically so you're not left estimating irradiance on your own.
A Few Common Questions
Do the Red (660nm) and NIR (850nm) wavelengths respond to distance the same way? Both follow the same inverse square law once they leave the panel, so distance affects Red light and NIR light equally in terms of irradiance. What differs is what happens after the light reaches your skin: NIR light penetrates deeper into tissue, while Red light interacts more with the surface layers. For more information on wavelengths, check out our guide here.
What if I'm somewhere between two of the listed distances? Small variations won't make or break a session. The listed distances are reference points, not exact lines you need to hit to the inch.
As with any new wellness routine, talk to a physician before starting regular red light sessions, particularly if you have an existing skin condition or are pregnant. Individual experiences vary, and RedRush panels are general wellness devices, not intended to diagnose, treat, cure, or prevent any disease.
