LED masks: what the wavelength numbers mean

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Researched. We have not used this one long enough to give you a verdict, and we would rather say so than invent one. What follows is how it works, who it suits, and what it will not do. When we have used it properly, this page carries the verdict and the date.

CurrentBody Skin Red Light Therapy Mask: Series 1

The number printed on the box of an LED mask — 633, 830, 415 — is a wavelength, measured in nanometres. It describes the colour of the light and nothing else.

It is not a strength, it is not a dose, and it is not a claim about results, although the way it is printed invites you to read it as all three.

Here is what the numbers correspond to, and then the number that actually decides anything, which most brands do not print.

What the wavelengths are

Around 415 nm — blue. The shortest wavelength in the consumer range, and the one that penetrates least. It stops at the surface. Blue is the range laboratory work has examined in relation to Cutibacterium acnes, a bacterium that lives in a pore and is involved in inflammatory breakouts. That work is about the organism under controlled conditions rather than about what a mask does to a face, and nothing on this page is offered as an answer to a skin condition.

Around 630 to 660 nm — red. Visible red, deeper than blue, and the wavelength most device marketing is built on. The claim attached to red concerns fibroblasts, the cells in the dermis that make collagen and elastin.

Around 810 to 850 nm — near-infrared. You cannot see it. A mask that appears to be doing nothing may be running its near-infrared diodes, usually with a faint red bleed from the LED package. Near-infrared goes deepest.

Depth is the entire reason the numbers differ. Longer wavelength, deeper penetration, roughly and with caveats. That is the mechanism, and it is why a mask sold around congestion and a mask sold around firmness carry different figures on the box.

The number that is missing

Wavelength tells you where the light goes. It tells you nothing about how much of it arrives.

The figure that governs that is irradiance — power per unit area, in milliwatts per square centimetre — multiplied by how long you wear the thing. That product is the dose, in joules per square centimetre, and it is the figure a clinical paper in this field would report.

Home masks run at a fraction of the output of the panels used in clinics. That is largely why they can be sold for unsupervised use at all. It is also why the session is twenty minutes rather than three, and why the honest unit of expectation here is months.

Very few consumer brands publish irradiance. Some publish it measured at the face of the diode rather than at the distance your skin actually sits, which is a different and much friendlier number. When a brand does give a figure and says where it was measured, that is worth more than an extra wavelength on the spec sheet.

Cleared, not approved

Most reputable LED masks sold in the United States hold an FDA clearance, granted under the 510(k) route. It is quoted constantly and understood rarely, so it is worth being precise about.

A clearance is a finding that a device is substantially equivalent to a device already legally on the market. It is not a finding that the device works, and it is not an approval — approval is a separate and far heavier process that these devices do not go through.

So "FDA-cleared" is a real fact and a modest one. It says the device sits in a regulated class, the maker filed, and the agency agreed it resembles something already being sold. It says nothing about whether the dose reaching your face is adequate.

The bit about eyes

Bright light held close to the eyes for twenty minutes at a time deserves to be taken seriously, particularly at the blue end.

Reputable masks either supply an opaque shield or keep the eye area dark, and their instructions tell you to keep your eyes shut. Follow the instructions rather than the reviews on the listing. If you have a retinal condition, that is a question for an ophthalmologist and not for a retailer.

Who it suits

Probably yes if you already have a routine you keep, and you are adding to it rather than rescuing it. LED asks for nothing but minutes, and unlike almost every other addition it does not compete with an acid or a retinoid for the same slot.

Probably not if you take anything that raises photosensitivity — some antibiotics, isotretinoin, certain diuretics, St John's wort among them. That is a question for whoever prescribed it, not for us and not for a brand's FAQ page.

Carefully, if melasma is the reason you are here. That kind of pigment responds to heat as well as to light, and a warm device pressed against the face for twenty minutes is heat.

What it will not do

• It will not show you anything in a fortnight. The research behind this category runs for weeks and measures modest differences.
• It will not work from inside a drawer. That is not a joke about willpower, it is the actual failure mode of the category. A dose delivered three times a week for three months is a different intervention from the same mask used enthusiastically for nine days and then not again.
• It will not stand in for sunscreen, and it does not undo a day spent without it.
• It will not reproduce the before-and-after on the advertisement, because that photograph is also doing lighting, angle and makeup.

The one thing that decides whether this works

Whether you will actually wear it.

Twenty minutes, three or four times a week, for three months, is somewhere between thirteen and seventeen hours of sitting still with a plastic shell strapped to your face. Before you spend anything, work out where in your week those twenty hours are.

If you cannot answer that, buy nothing yet. This is not a soft conclusion. It is the same reasoning that makes a cheap product you use beat an expensive one you do not, and it applies harder here than anywhere else on the shelf, because this is the only category where the cost is measured in time rather than in millilitres.

The product

It names both of its wavelengths on the box, 633 and 830 nanometres, which is more than a good deal of the category manages, and it holds a clearance rather than only a marketing page. It is a flexible mask rather than a rigid shell, which matters more than it sounds when the requirement is twenty minutes at a time, several times a week, for months.

The one people are searching for is the CurrentBody Skin Red Light Therapy Mask: Series 1.

CurrentBody Skin Red Light Therapy Mask: Series 1

We do not print prices here, because a price we typed last month is a price that is wrong today.

Written by JamieG in Garner Town, Tennessee.