Why can we feel infrared light but not ultraviolet rays?
Understanding the Science Behind Infrared Saunas and Light Wavelengths
Can an infrared sauna cause sunburn or tan your skin? It’s a common question—especially for people new to sauna therapy. The short answer is no, infrared saunas do not tan or burn your skin, and they do not emit UV rays. But why do you feel heat from infrared light and not from ultraviolet (UV) light? Let’s break down the science.
Infrared vs. Ultraviolet: What’s the Difference?
The key lies in the electromagnetic spectrum, which organizes types of light based on wavelength. Here’s how it works:
Light Type | Wavelength Range | Perceived Effect | Risk Level |
|---|---|---|---|
Ultraviolet (UV) | 10–400 nanometers | Invisible, damages DNA | High (sunburn, cancer) |
Visible Light | 400–700 nanometers | Seen as color | Minimal |
Infrared (IR) | 700 nm – 1 mm | Felt as heat | Safe (non-ionizing) |
Infrared (IR) is on the longer wavelength side, which means its photons carry less energy, but it vibrates water molecules in your body, producing heat.
Ultraviolet (UV) has shorter wavelengths and more energetic photons, which can damage cells and DNA, but you don’t feel it immediately.
Why Infrared Light Feels Warm
Infrared light penetrates your skin and interacts with water molecules, causing them to vibrate and generate heat. This heat is what you feel in a far infrared sauna. It’s why sauna sessions feel deeply warming and relaxing.
SaunaCloud’s custom saunas are engineered with VantaWave™ far infrared heaters that emit wavelengths centered around 7.9 microns—a sweet spot for deep tissue penetration and safe core temperature elevation.
✅ This range falls directly within the therapeutic far infrared spectrum (5.6 to 1000 microns), not near-infrared (0.75 to 1.4 microns), which is too shallow to deeply heat the body.
Why You Don’t Feel UV Rays—Until It’s Too Late
UV light doesn’t make you feel warm because it doesn’t vibrate molecules the way infrared does. Instead, UV is ionizing radiation, which means it can break molecular bonds, damaging DNA and leading to sunburns, premature aging, and even skin cancer.
UV exposure symptoms show up hours later—not immediately, like the heat from infrared light.
So, to be clear:
An infrared sauna will NOT cause tanning, sunburn, or UV damage.
Why Far Infrared is Ideal for Human Health
Your body actually emits and absorbs infrared radiation naturally. The peak emissivity of human skin is around 8–10 microns, meaning it’s finely tuned to both produce and absorb far infrared wavelengths. That’s why far infrared saunas feel so natural and restorative.
In comparison:
Near-infrared (NIR) light (used in some LED red light therapy devices) doesn’t generate heat and is not typically used as a primary heat source.
Most “full spectrum” infrared saunas include halogen heaters, which provide intense heat, but often aren’t necessary for smaller or properly insulated custom infrared saunas.
Summary: Why Infrared Is Safe, Effective, and Nothing Like UV
Infrared saunas use far infrared light, which safely heats your body by resonating with water molecules.
Ultraviolet light does not produce heat but instead causes cell damage over time.
SaunaCloud saunas target the optimal wavelength for health and comfort—7.9 microns at 190–200°F surface temperature.
You’ll never tan or burn in an infrared sauna—but you will sweat, detox, and heal.
Final Takeaway
Infrared light is the perfect wavelength to raise your core temperature naturally and safely. Unlike ultraviolet rays, which are dangerous and damaging, far infrared saunas deliver therapeutic heat your body is built to receive. That’s why more people are turning to infrared therapy as a trusted, science-backed way to improve their health.
