1. The Right Wavelengths
The first thing I looked at was the wavelengths being used.
The wavelengths that appeared repeatedly throughout the research were:
• 633nm Red Light
• 830nm Near-Infrared Light
These are among the most studied wavelengths in skin rejuvenation and photobiomodulation research.
If a mask wasn't using wavelengths close to these, I immediately crossed it off my list.
2. Adequate Power Density (Irradiance)
The next factor was irradiance, sometimes called power density.
This is usually measured in milliWatt per centimeter squared(mW/cm².)
Think of this as how much light energy is actually reaching your skin.
For at-home devices, around 30-50 mW/cm² is often considered an effective range.
Too little power and the treatment may not be effective.
Too much power and you can generate unnecessary heat, which can cause heat related skin issues.
3. Effective Dose (Joules)
The third factor was dose.
Dose is measured in Joules per square centimeter (J/cm²).
This is determined by both the power of the device and how long you're exposed to the light.
While different studies use different protocols, many popular at-home masks deliver around 18 J/cm² per treatment session.
Too little may not provide enough stimulation.
Too much may create unnecessary heat and longer treatment times.
The goal is finding a mask that delivers an effective dose in a practical amount of time.
4. Close Contact With The Skin
This was one factor I almost overlooked.
The closer the LEDs are to your skin, the more efficiently the light can be absorbed.
That's why flexible masks that sit directly against the face often have an advantage over devices that sit several inches away.
Better contact can help improve light delivery while making treatments easier to fit into a daily routine.
Once I understood these four factors, I stopped looking at marketing claims and started comparing masks based on what actually mattered.