How Long Does It Take for Red Light Therapy to Work?

Red light therapy (RLT) is a well-established, non-invasive treatment. It is used in skin rejuvenation, pain relief, hair loss, and wound healing, among others, although research on effectiveness is still emerging. As the therapy demands patience, it's important to understand the timelines for seeing the desired results. Join us as we summarize the application-specific treatment durations of red light therapy.

How does red light therapy work?

Red light therapy was first discovered by Dr. Endre Mester back in 1967. However, the therapy received a sound footing only after Tiina I. Karu, a biophysicist, elucidated its underlying mechanism in 2008.

Red light therapy essentially works via photobiomodulation, or the use of low-power light, to stimulate tissue repair. It is thought to activate a key enzyme in the body's cells and stimulate mitochondria, which, in turn, can boost the production of energy in cells (ATP). It can further accelerate cell growth and RNA and protein production, as well as relieve oxidative stress. The emerging evidence suggests that red light therapy may be beneficial for managing certain health conditions, but further research is needed to know for sure.

Researchers have been exploring the utility of red light therapy for a broad range of applications. These include muscle injuries, nerve injuries, depression, anxiety, myopia, acne, weight loss, and sleep disorders. However, substantial evidence has been gathered only for a few of them.

Red light therapy displays bi-phasic dose response, meaning light exposure below the threshold won't show any effects, and too much exposure would cause bio-inhibition instead of stimulation. Identifying the appropriate dose is not easy and demands more studies.

Personal responses to red light therapy show a lot of variation. Therefore, it is wise to start with trial exposure and proceed to higher doses gradually.

How long it takes for red light therapy to work

Understanding the proposed mechanisms and benefits, how long does red light therapy take to work in reality? Like other treatments of a non-invasive nature — such as physical therapy — red light therapy takes some time before results become evident.

Sometimes, people experience improvement after just one treatment for acute issues, such as acute neck pain. However, for chronic conditions, it typically takes multiple treatments over weeks to months to notice significant and lasting benefits.

Based on the application, the red light therapy practitioner will decide the appropriate treatment regimen, including illumination parameters and treatment timing.

Studied red light therapy timelines for common uses

Effects of photobiomodulation are materialized through a cascade of changes at molecular, cellular, and tissue levels, which are incompletely understood. There is a large number of illumination parameters such as wavelength, fluence, power density, and pulse structure to choose from. Finding the right combination of frequency-duration of treatment isn't easy either.

All this explains the lack of standardized treatment protocols. In this article, we are considering only the well-established applications of red light therapy that have clinical evidence.

Skin health and anti-aging

There is some evidence to suggest that red light therapy may be effective in reversing skin damage and signs of aging. Skin rejuvenation may occur through the activation of stem cells, which may help reduce fine lines, wrinkles, and skin roughness while increasing intra-dermal collagen production.

Red light therapy is also being investigated for its potential use in the management of psoriasis, pigment disorders, and the healing of burns. While the emerging evidence is promising, more research is needed to fully establish its use for these skin conditions.

Much work has been put towards narrowing down the most effective treatment parameters. The use of an LED face mask Skin Light Dior X Lucibel mediated therapy resulted in lasting — up to 1 month — skin rejuvenation. The device utilized red light with a wavelength of 630 nanometers (nm) and a power of 15.6 Joules per square centimeter (J/cm2). The treatment regimen consisted of two sessions per week, each lasting 12 minutes, for three months.

Another controlled trial reported good efficacy with red light exposure at a wavelength of 611 and 650 nm for 12–25 minutes twice a week for 15 weeks.

In 2021, a research group from China investigated red light therapy for moderate-to-severe Acne vulgaris treatment. It involved 630 and 890 nm red light wavelength exposure, once in 7 or 14 days, and the treatment was continued for between 2 and 12 weeks. Nevertheless, red light therapy didn’t prove to be more effective compared to conventional therapies.

Pain relief

Limited research data is available in this area, and the exact mechanism behind red light therapy is still under investigation. However, some studies show that it can potentially reduce inflammation and increase cell proliferation to relieve pain.

Red light therapy (640–905 nm) has shown some benefit in fibromyalgia, neck pain, back pain, and pain after total hip replacement surgery. In clinical trials, the therapy duration has varied widely, with some studies showing that 5–10 minutes for one to two sessions per week may help reduce the intensity of pain. The therapy relieved acute neck pain almost immediately, while chronic pain demanded therapy till 22 weeks.

Low-level laser therapy improved the pain and disability in knee osteoarthritis patients by reducing chronic inflammation. A systematic review mentions the administration of red light between 785 and 904 nm for two to five sessions per week for up to 12 weeks.

A systematic review demonstrated that undergoing red light therapy for up to nearly 7 minutes just before exercise improved flexibility and reduced muscle fatigue.

Hair growth

Red light therapy may improve the regeneration of scalp hair follicles. For the treatment of androgenetic alopecia, a bicycle helmet-like apparatus, TOPHAT655, was designed. It irradiated the scalp with 655 nm light for 25 minutes every day for 16 weeks and remarkably improved hair count.

Another study reported the therapy continuation till 26 weeks.

Wound healing

Fibroblasts produce collagen and maintain the tissue structure, while keratinocytes are responsible for the barrier function of the skin. Both types of cells are important in wound healing.

Red light therapy is thought to accelerate their growth, in addition to normalizing the blood flow, and thus potentially restores the body's natural healing process. These changes may lead to faster wound closure, healing, and reduction in scar tissue.

Many studies mention the continuation of daily therapy until healing. In the case of wounds, doing red light therapy with medical supervision is highly recommended.

Preclinical studies on cell lines and rats demonstrated the positive effects of red light therapy for diabetic wounds through the regulation of inflammation, cell growth, and cell migration. The exposure durations for patients were between 8 and 50 minutes.

Factors influencing the effectiveness of red light therapy

It is hard to predict the effectiveness of red light therapy. In addition to device characteristics and red light therapy parameters, the overall health status of an individual determines their response. Attributes of the disease such as acute or chronic nature and location of the treatment area also impact the timeline for seeing results.

Photobiomodulation therapy is presumed to trigger several cellular pathways, leading to stepwise activation of chemical reactions. This would take some time to reach the maximum efficiency. Therefore, the latest research suggests that rather than having daily sessions, it is more advantageous to have a break of 72 hours between the sessions.

Professional treatment vs. at-home red light therapy devices

There are no comparative studies available to evaluate the difference as of yet. Some people may prefer at-home devices because of their cost-effectiveness and flexibility. However, we can expect that professional treatment centers would have FDA-cleared or approved red light therapy devices with better safety profiles. Also, experienced practitioners may be able to help with treatment plan design and achieve results faster.

With big panels having numerous LED lights, it's possible to administer light therapy for the entire body. Such exposure speeds up therapeutic sessions, unlike hand-held devices that irradiate a single spot at a time.

Maximizing the effectiveness of red light therapy

It is important to choose the right wavelength depending on the depth of tissue penetration. Visible red wavelengths ranging from 600 to 700 nm are suitable for superficial skin applications, while the near infra-red wavelengths (780–950 nm) are suitable when deep tissue penetration is desired.

Red light therapy works at a cellular level, so it may take time to produce visible results; the improvements are likely to build over time. Therefore, it is crucial to have patience and be consistent to get noticeable and stable results.

A wide range of devices including red light therapy beds, infra-red sauna blankets, big panels, face masks, massagers, wrap belts, and hand-held wands are available. These devices usually fall under the general wellness device category or class I and II medical device category, indicating minimal risk. Class I medical devices are associated with low to moderate risk, while class II devices are associated with moderate to high risk and require special controls.

It's necessary to confirm the FDA approval/clearance status of the RLT device when making a choice. Consult your healthcare provider when choosing the device.

Final word

Red light therapy holds great potential as an alternative therapy. It is safe and non-invasive but may take time to show visible signs. Choosing an FDA-cleared or approved red light therapy device, following an expert-designed treatment plan, and maintaining consistency in undergoing red light therapy are the key elements.

If you've used red light therapy for health/cosmetic purposes, kindly share your feedback in the comments below.