When you buy a red light therapy device, you'll usually see two wavelengths listed: 660nm (red) and 850nm (near-infrared). These wavelengths work on different tissues and produce different effects. Understanding the difference is key to choosing the right device and using it correctly.

The Basics: What Are These Wavelengths?

Light is electromagnetic radiation, and its wavelength (measured in nanometers) determines its properties. The visible light spectrum ranges from about 380nm (violet) to 750nm (red). Beyond 750nm is infrared, which is invisible to the human eye.

  • Red light (630–700nm): Visible red light. You can see it. The therapeutic sweet spot is 660nm, with 633nm also common in masks.
  • Near-infrared (NIR, 800–1000nm): Invisible to the human eye. The therapeutic sweet spot is 830–850nm. 810nm is studied for brain effects.

Both wavelengths are absorbed by cytochrome c oxidase (CCO) in your mitochondria, but they have different absorption efficiencies and penetrate to different depths. This is why they produce different effects in the body.

Penetration Depth

Light penetration into tissue depends on wavelength. Shorter wavelengths (red) are absorbed closer to the surface; longer wavelengths (NIR) penetrate deeper.

WavelengthPenetration DepthPrimary Target
633nm (red)1–2 mmEpidermis (outer skin)
660nm (red)2–5 mmDermis (inner skin)
810nm (NIR)5–10 mmSubcutaneous tissue, brain
830nm (NIR)5–10 mmSubcutaneous tissue, muscle
850nm (NIR)5–10 mmMuscle, joint, bone

Notice that red light barely reaches the dermis (the deeper skin layer where collagen is made), while NIR reaches muscle and joint tissue. This is why red light is better for surface skin concerns, while NIR is better for deeper issues like muscle pain and joint inflammation.

What Each Wavelength Does

Red Light (660nm) Effects

  • Stimulates collagen production in the skin
  • Reduces surface inflammation (acne, eczema)
  • Speeds wound healing
  • Improves skin tone and texture
  • Reduces fine lines and wrinkles

Near-Infrared (850nm) Effects

  • Reduces deep tissue inflammation (joint, muscle)
  • Speeds muscle recovery after exercise
  • Reduces arthritis pain
  • Treats tendonitis and other deep-tissue injuries
  • Improves circulation to deep tissues
  • May have neuroprotective effects (810nm in particular)

Which Wavelength Do You Need?

For Skin Concerns (Wrinkles, Acne, Eczema)

You mostly need red light (660nm or 633nm). A pure red light device (like the Solawave wand) will work. However, NIR adds some benefit by stimulating fibroblasts deeper in the dermis, so a combined device is slightly better.

For Pain and Recovery

You need NIR (850nm). A red-light-only device won't help with deep tissue pain. Choose a panel or wrap that delivers both 660nm and 850nm — the red light helps with surface inflammation, but the NIR does the heavy lifting for pain.

For Hair Regrowth

You need 655–670nm red light (LLLT devices like iRestore). NIR is not used for hair regrowth — the wavelength is too long to optimally stimulate hair follicles.

For General Wellness

A combined 660nm + 850nm panel is ideal. It addresses both surface (skin) and deep (muscle, joint) tissues, making it the most versatile choice.

Why Most Devices Combine Both

Most quality red light therapy panels and masks combine 660nm and 850nm (or 633nm and 830nm). The reason is simple: combined wavelengths address a broader range of concerns in a single device, making the device more versatile and cost-effective.

The combined approach also has synergistic effects. Red light reduces surface inflammation, allowing NIR to penetrate more effectively. NIR stimulates deeper tissues, supporting the surface repair work being done by red light. The two wavelengths work better together than either alone.

If you're buying your first device, get one with both wavelengths. It's the most versatile choice and will address the widest range of concerns.

Frequently Asked Questions

Some devices let you toggle wavelengths on and off. For most users, using both together is fine and more efficient. If you want to focus on skin only, you can turn off NIR. If you want to focus on deep tissue pain, you can turn off red light — but the slight surface benefit from red light isn't wasted.
Both wavelengths are safe at recommended doses. NIR is invisible, which means you don't blink or look away instinctively — making eye protection even more important with NIR-enabled devices.
Human eyes can only detect light from about 380nm (violet) to 750nm (red). NIR (800–1000nm) is beyond our visual range. The device looks "off" when NIR is on, but it's actually emitting intense invisible light. This is why NIR-enabled panels feel warm — you're feeling the light, not seeing it.
Slightly. NIR is closer to the infrared spectrum (which we feel as heat), so NIR-emitting panels can feel warm on the skin. This isn't a side effect — it's just the light energy being absorbed by tissue. The warmth is mild and not the primary therapeutic effect.
Both are effective. 830nm is more common in clinical research; 850nm is more common in commercial devices. The difference is minor — both wavelengths target the same deep tissues. Don't overthink this choice.
Partially. Sunlight contains red and NIR light, but also contains UV (which damages skin) and is unpredictable in intensity. RLT devices deliver therapeutic doses of red/NIR without the UV risk. That said, 10–15 minutes of morning sunlight on bare skin has benefits similar to a low-intensity RLT session.

Get Both Wavelengths

The MitoMAX 2.0 delivers both 660nm and 850nm — the most versatile combination for skin, pain, and recovery.

Check on Amazon →