The Science Behind LED Light Therapy

Introduction: What is LED light therapy?

LED light therapy, also known as photobiomodulation (PBM), is an advanced, non-invasive treatment that uses specific wavelengths of visible and near-infrared light to stimulate the skin and improve cellular processes. Unlike ultraviolet (UV) light, which can be harmful to the skin, the wavelengths used in LED therapy work in a safe, therapeutic way (Cleveland Clinic, 2025).

The mechanism behind this is remarkably elegant: when light of certain wavelengths reaches the skin, it is absorbed by a key enzyme in our cells — cytochrome c oxidase — which is located in the mitochondria, the ‘powerhouses’ of our cells (Hamblin, 2018). This process leads to an increase in ATP (adenosine triphosphate), the energy currency of our cells. With more cellular energy, skin cells have a greater capacity to repair and regenerate themselves (Dompe et al., 2020).

This process is known as photobiomodulation and is a natural way to stimulate the skin from within — without chemicals, invasive procedures or UV radiation.

The proven benefits of LED light therapy

Research has shown that LED light therapy offers numerous benefits for the skin and the body. The best-documented effects are:

LED therapy activates fibroblasts — the cells responsible for producing collagen and elastin (Hamblin, 2018). This leads to visibly improved skin elasticity, reduced wrinkles and a more youthful appearance (Lee et al., 2007; Ablon, 2018).

LED light helps to regulate inflammatory responses, which is particularly beneficial for people with acne, rosacea or sensitive skin (Dompe et al., 2020).

By enhancing cellular energy production, LED therapy accelerates the skin’s natural healing process following damage, scarring or dermatological procedures (Ryu et al., 2022).

Regular LED treatments stimulate blood circulation in the skin, thereby improving the delivery of oxygen and nutrients to the skin cells (Curtis et al., 2013).

LED light helps to strengthen the skin’s immune system and aids the recovery of damaged skin from UV radiation and environmental stress.

However, the effectiveness of LED therapy depends heavily on the wavelength of the light used. Different wavelengths penetrate the skin to different depths and trigger different biological processes. That is why choosing the right wavelengths is essential.

Wavelengths explained

Light behaves like waves, and each wavelength — measured in nanometres (nm) — penetrates the skin to a different depth and activates different biological mechanisms. Here’s how it works:

• ✓Blue light (400–495 nm) penetrates mainly into the superficial layers of the epidermis.
• ✓Red light (600–700 nm) penetrates deeper into the dermis, to a depth of approximately 4–5 mm.
• ✓Near-infrared (NIR) light (700–1000 nm) penetrates the deepest, passing through all layers of the skin and into the underlying tissues.

These differences in penetration depth are crucial, as they determine which processes in the skin can be activated. For optimal skin rejuvenation, a multi-wavelength approach is ideal — different wavelengths that work together to create synergistic effects (Ash et al., 2017).

Our five light settings: why each wavelength was chosen

1. Red light (630 nm)

At 630 nm, the light penetrates to a depth of approximately 4–5 mm into the skin, which is ideal for effectively reaching the dermis — the middle layer of the skin where collagen and elastin are found (Ash et al., 2017).

The proven effects of 630 nm red light:

• ✓Stimulates fibroblasts to produce collagen and elastin
• ✓Visibly reduces fine lines and wrinkles
• ✓Improves skin texture and gives a natural glow
• ✓Accelerates wound healing and cell regeneration
• ✓Promotes a more even skin tone

A groundbreaking study found that treatment with 630 nm LED light for 20 minutes significantly increased the cell viability and proliferation rate of skin cells — with a more than threefold increase in cell migration (Ryu et al., 2022).

Another study showed that 630 nm combination treatments (combined with near-infrared light) resulted in a demonstrable improvement in skin elasticity and youthfulness over a period of 8–12 weeks (Park et al., 2025).

Optimal dosage and schedule for red light (630 nm):

• ✓Session duration: 15 minutes per session
• ✓Frequency: 3–4 times a week for the first 4–6 weeks (initial treatment period)
• ✓After that: once or twice a week for maintenance

This regimen allows your skin to respond to the treatment gradually. After 4–6 weeks of consistent use, you will notice a clear improvement; after that, using it once or twice a week is sufficient to maintain the results.

2. Blue light (450 nm)

Blue light at 450 nanometres is the gold standard for acne treatment. This is the wavelength used in FDA-approved professional devices and has been shown to effectively combat acne-causing bacteria in dozens of clinical trials (Sadowska et al., 2021).

At this wavelength, the light is safe — research shows that 453 nm blue light has no adverse effects on healthy skin cells, even at very high doses (Liebmann et al., 2011). At the same time, it triggers an elegant microbiological process.

Acne bacteria (Cutibacterium acnes) contain a pigment called coproporphyrin. When blue light at 450 nm reaches this pigment, a chemical reaction is triggered that produces singlet oxygen — a reactive form of oxygen that kills the bacteria (Liang et al., 2022; Liebmann et al., 2021). It is not a general inflammatory response, but a targeted, bacterial action without the side effects of antibiotics.

The proven effects of 450 nm blue light:

• ✓Kills acne-causing bacteria without damaging the skin
• ✓Reduces inflammation and redness caused by acne
• ✓Regulates excessive sebum production
• ✓Prevents new spots from forming without drying out the skin
• ✓Promotes the healing of existing acne lesions

A meta-analysis of six clinical studies involving 216 participants found that blue light LED devices result in a 45.3–47.7% reduction in acne spots (Barbieri et al., 2025). Improvement is usually visible after 4–12 weeks of regular use.

A specific study followed 24 patients with moderate acne. After just 2 weeks, 45.8% reported a ‘good’ or ‘excellent’ result; after 8 weeks, 75% had a ‘good’ to ‘excellent’ result (Lee et al., 2007).

Optimal dosage and schedule for blue light (450 nm):

• ✓Session duration: 15 minutes per session
• ✓Frequency: 3–5 times a week for at least 4–6 weeks
• ✓After that: once or twice a week for maintenance

With blue light, regularity is even more important than with red light: consistent treatment prevents acne from returning. Many users notice fewer red spots and less inflammation after just 2–3 weeks.

3. Yellow light (580 nm)

Yellow light at 580 nanometres is relatively new in the world of LED therapy, but the research findings are impressive. This is the ‘gentle’ wavelength — it penetrates only superficially (just 0.5–2 mm), making it ideal for sensitive skin, rosacea and inflamed skin (Weiss et al., 2005).

The proven effects of 580 nm yellow light:

• ✓Reduces redness and inflammation without causing irritation
• ✓Promotes lymphatic drainage (reduces swelling and puffiness)
• ✓Improves blood circulation in the superficial layers of the skin
• ✓Helps with melasma and pigmentation problems
• ✓Stimulates collagen production at a gentler, slower pace (ideal for sensitive skin)
• ✓Soothes irritated skin and restores the skin barrier

Recent research (2025) showed that 570–590 nm yellow light, combined with red and near-infrared light, significantly improved wrinkles and skin texture after just 8 weeks of treatment, three times a week. 570 nm was slightly more effective than 590 nm for wrinkle reduction and brown spots (Park et al., 2025).

Another study found that 590 nm yellow light effectively treats melasma: after eight weeks, the melasma severity score improved by an average of 23.3% without any serious side effects (Dai et al., 2022).

Optimal dosage and schedule for yellow light (580 nm):

• ✓Session duration: 15 minutes per session
• ✓Frequency: 2–3 times a week for sensitive skin, up to 4–5 times a week for normal skin
• ✓After that: once or twice a week for maintenance

Yellow light can be used more frequently and safely than red or blue light, as it acts on the surface and does not ‘overload’ the skin as quickly.

4. Near-infrared (NIR) light (850 nm)

850 nanometres is at the very edge of what the human eye can see (infrared is invisible, but you can feel it as heat). This is where the real work happens.

850 nm penetrates deeper than any other wavelength — much deeper than red or blue light. Not only does it reach deep into the dermis, but it can even pass through the subcutaneous fat to reach the connective tissue (Ash et al., 2017; Hamblin, 2018). This makes 850 nm ideal for deeper cellular regeneration, inflammation reduction and tissue repair.

The proven effects of 850 nm near-infrared light:

• ✓Highly effective for stimulating collagen and elastin at a deeper level
• ✓Significantly reduces inflammation in the deeper layers of the skin
• ✓Accelerates wound healing and scar repair
• ✓Supports skin and tissue regeneration
• ✓Effective for post-acne scars and skin texture issues
• ✓Promotes skin firmness
• ✓Supports skin revitalisation and antioxidant protection

A double-blind study (2007) found that combination therapy using 630 nm and 830 nm reduced wrinkle depth by up to 36% and improved skin elasticity by 19%, without any side effects (Lee et al., 2007).

A more recent study (2025) showed that professional LED and near-infrared treatments at 850 nm are "effective, safe, well-tolerated and painless" for skin rejuvenation (Park et al., 2025).

Optimal dosage and schedule for near-infrared (850 nm):

• ✓Session duration: 15 minutes per session (may be longer than the red light)
• ✓Frequency: 3–5 times a week for the initial treatment
• ✓After that: once or twice a week for maintenance

Because 850 nm penetrates deeply, it can be used for longer without causing skin irritation.

5. Purple light (combination of red and blue)

Purple light is not a single wavelength — it is an intelligent combination of red (630 nm) and blue (450 nm) light. This is scientifically proven and creates a synergistic effect: the combined effects are greater than the sum of their parts.

Red light penetrates deeper and stimulates collagen in the dermis; blue light acts on the surface and destroys acne-causing bacteria. Together, they treat both acne and its associated scars and redness (Liang et al., 2022). Particularly valuable for active acne with redness, post-acne scars and combination skin problems.

The proven effects of purple light (red + blue):

• ✓Kills acne-causing bacteria (blue) whilst stimulating collagen production (red)
• ✓Reduces both active spots and post-acne scars
• ✓Soothes redness and inflammation at the same time
• ✓Provides greater skin improvement than red or blue light alone
• ✓Ideal for youthful skin with multiple concerns

In a controlled study, patients were exposed to alternating blue (415 nm) and red (633 nm) light twice a week. After 2 weeks, 45.8% reported a ‘good’ or ‘excellent’ result; after 8 weeks, this had risen to 75% (Lee et al., 2007). A meta-analysis (2025) concluded that the benefits were particularly evident when devices incorporated both colours (Barbieri et al., 2025).

Optimal dosage and schedule for purple light:

• ✓Session duration: 15 minutes per session
• ✓Frequency: 3–4 times a week for the initial treatment (4–6 weeks)
• ✓After that: once or twice a week for maintenance

Purple light can be used as an "all-in-one" setting, particularly for those who have multiple skin concerns or are unsure which wavelength is required.

Professional appliances vs. domestic appliances

Professional devices deliver higher power levels (40–150 mW/cm²) than most home devices (1–30 mW/cm²), leading to faster results in fewer sessions (Turner, 2025). However, home devices often work better for long-term results — and the reason is simple: consistency beats speed.

Research shows that the real benefits of LED therapy do not come from a few intense sessions, but from regular, consistent use over time (Lee et al., 2007; Ablon, 2018). Think of it like exercise: one intense workout helps, but training three times a week is what really builds your body.

The benefits of home use:

• ✓Consistency: Treat yourself at home 3–4 times a week without the need for appointments, travel or waiting.
• ✓Long-term compliance: regular use at home yields better results than occasional clinic visits.
• ✓Cost-effective: a home device is a one-off purchase; a clinic costs €50–200 per session.
• ✓Control: you decide on your own treatment plan and adapt it to suit your needs.

A systematic review concluded that home LED therapy, provided it is used regularly and employs high-quality LEDs with sufficient power density, is just as effective as professional devices (Cios, 2021; Turner, 2025). The key is consistency: 2–3 times a week, week after week.

The Safety of LED Light Therapy: Fact and Fiction

The short answer: yes, very safe, provided it is used correctly.

LED light does not use ionising radiation (such as UV or X-rays). It does not damage your DNA and does not cause cancer (Colaz, 2025). Instead, it naturally stimulates your cells to produce more energy — something your body already does.

Most studies report no serious side effects; the Cleveland Clinic states that "serious side effects are rare" (Cleveland Clinic, 2025). Possible mild side effects associated with excessive use:

• ✓Mild redness or a sensation of warmth (usually disappears within 24 hours)
• ✓Mild dryness (very rare)
• ✓Eye strain when looking into the light (which is why eye protection is built in)

How to prevent side effects:

• ✓Please stick to the recommended usage time: 15 minutes per session (SolarMask has a fixed 15-minute auto-timer), no longer.
• ✓Stick to the recommended frequency: 3–4 times a week, not every day without a rest day.
• ✓Do you have very sensitive skin? Start with a shorter duration and build up gradually.

Special groups — if you are pregnant, taking light-sensitive medication, have a history of cancer or suffer from eye problems: consult your doctor first. For most healthy people, LED therapy is completely safe when used as intended.

Conclusion: a scientifically informed choice

LED light therapy is not just a pipe dream — it is scientifically proven, clinically validated and safe. Our five wavelengths have not been chosen at random, but are the result of years of research, clinical trials and practical application:

• ✓630 nm red light — the most proven wavelength for skin rejuvenation
• ✓450 nm blue light — the gold standard for acne treatment
• ✓580 nm yellow light — ideal for sensitive skin and pigmentation
• ✓850 nm near-infrared — penetrates deeply and stimulates thorough regeneration
• ✓Purple (red + blue) — mixed benefits for complex skin problems

With regular use (3–4 times a week, 15 minutes per session), you can expect:

• ✓After 2–4 weeks: reduced acne and less redness
• ✓After 4–8 weeks: visible improvement in skin texture and a reduction in fine lines
• ✓After 8–12 weeks: significant improvement in wrinkles, elasticity and radiance
• ✓After that: 1–2 times a week to maintain the results

Your skin already has all the tools it needs. LED light simply gives it the energy to make the most of those tools.