The Science Behind Red Light Therapy for Hair Loss13 min read

You might have come across red light therapy if you’ve been looking into hair loss solutions for a little while. Red Light Therapy (RLT) involves using specific red light wavelengths to gently stimulate hair follicles and improve scalp health. Known for its gentle, non-invasive approach, this approach is gaining attention for its role in supporting hair growth. In this guide we talk about the biology and intricacies of red light therapy for hair growth to help you understand how this treatment may benefit you. Initially developed for plant growth in space (yes!), RLT effectiveness in promoting human tissue regeneration, particularly for hair – was a later discovery.

Understanding Red Light Therapy

The Science Behind RLT

Red Light Therapy (RLT) operates on the principle of photobiomodulation (“photo” = light, “bio” = life: modulation life by light, or low level light therapy), where specific wavelengths of red light, typically between 630 and 700 nanometers, are used to interact with cells in your body. When this light penetrates the skin, it reaches the mitochondria, “a power engine” of a cell, stimulating them to produce more energy. This increase in cellular energy is believed to support various healing and rejuvenating processes in the body.

Red Light’s Effect on Hair Growth

Beneficial impact of red light therapy on hair growth comes from its ability to interact with cells and tissues in a way that supports hair follicles and enhances blood circulation to the scalp. Here’s how it works:

  • Cellular Energy Boost: Red light, with its specific wavelengths, is absorbed by chromophores within cells, particularly those found in the mitochondria (as pictured above). One crucial enzyme in the mitochondria, cytochrome c oxidase (CCO), is known to absorb red light due to its iron content. When CCO absorbs red light, it becomes more active, leading to an increase in the production of adenosine triphosphate (ATP), which is the primary energy currency of cells.
  • Hair Follicle Stimulation: Hair follicles are among the most metabolically active structures in your body, requiring a significant amount of energy to function optimally. When red light therapy stimulates the production of ATP in the surrounding cells, this enhanced energy supply directly benefits the hair follicles directly. It can lead to improved cellular function, including the synthesis of proteins necessary for hair growth.
  • Enhanced Blood Circulation: RLT also has a vasodilatory effect on blood vessels, meaning it widens them. This vasodilation can result in increased blood flow to the scalp. As a consequence, more oxygen and nutrients are delivered to the hair follicles. Improved blood circulation is vital for maintaining the health of hair follicles and promoting hair growth.
  • Reduced Inflammation: Inflammation can negatively impact hair follicles and contribute to hair loss: scalp inflammation is especially known to attract DHT in people prone to androgenic alopecia (people with PCOS, perimenopausal women and male pattern baldness). RLT has shown to have anti-inflammatory effects, and by reducing inflammation, it creates a more favorable environment for hair growth.

Safety Considerations

Regarding safety, RLT is generally considered safe, with minimal side effects reported. However, it’s important to use devices according to manufacturer guidelines and to consult with a healthcare professional, especially if you have skin conditions or are taking medications that might increase light sensitivity.

The Benefits of Red Light Therapy for Hair

How Red Light Promotes Hair Growth

Red light therapy’s ability to promote hair growth is rooted in its capacity to energize and stimulate hair follicles, as described above. By enhancing cellular activity and nutrient supply to the scalp, it creates a “busy”, conducive environment for hair growth. This process results in healthier, thicker hair; but let’s dive deeper into this claim and look into the science:

hair growth cycles under red light therapy

Red light therapy (RLT) affects the anagen (growth) and catagen (shedding) stages of hair growth by promoting anagen and delaying catagen. Here’s how RLT influences these stages:

1. Anagen Phase (Growth Phase) and Red Light Therapy:

  • Promotion of Anagen Phase: RLT stimulates the hair follicles during the anagen (growth) phase, encouraging the growth of new hair strands. Cells absorb the specific (650-655nm) wavelengths of red light, particularly those in the mitochondria. This absorption triggers an increase in adenosine triphosphate (ATP), the “energy fuel” that cells create upon converting sugars, which provides energy for cellular activities. In the context of hair follicles, this increased energy can lead to enhanced hair growth during the anagen phase.
  • Faster Hair Regeneration: By supplying additional energy to hair follicles, RLT can potentially accelerate the regeneration of new hair. This means that hair may grow back faster after shedding or damage.

2. Catagen Phase (Transitional Phase) under Red Light:

  • During catagen hair detaches itself from the blood supply and begins to enter “resting” stage of hair growth. Catagen means that the hair is on its way out. Red light therapy, however, specifically 655-nm wavelength, can reduce the transition to the catagen phase in human hair follicles, promoting longer periods of hair growth. Studies indicate that such therapy not only enhances hair shaft elongation but also delays the onset of catagen, extending the anagen (growth) phase of the hair cycle. Therefore, red light therapy tends to delay the catagen phase, supporting longer hair growth periods.

How to Use Red Light Therapy for Hair

Different Types of RLT Devices

Various types of red light therapy devices are available for hair treatment, each with its unique features and advantages. Here’s an overview of the most common types:

red light devices for hair growth, red light therapy for hair
  • Handheld Devices: These portable devices are designed for targeted treatment. They are convenient for spot treatments on specific areas of the scalp and are often used for home-based therapy.
  • Helmets and Caps: Helmets and caps equipped with red light diodes provide more extensive coverage of the scalp. They are designed for hands-free and full-scalp treatments, making them a popular choice for those looking for a hassle-free experience.
  • Combs and Brushes: Some RLT devices come in the form of combs or brushes with embedded red light diodes. These devices allow for a combination of scalp massage and therapy, promoting both circulation and hair growth. They also allow for the separation of the existing hair to reveal and avail the scalp for the reception of red light.
  • In-Clinic Devices: For professional treatments, specialised RLT machines are available at dermatology clinics and hair restoration centres. These devices offer high-intensity treatments which physicians use in conjunction with other therapies for comprehensive hair restoration.

Recommended Treatment Protocols

The effectiveness of RLT for hair growth depends if you use it consistently and appropriately. While specific protocols may vary depending on the device and individual needs, here are some general recommendations:

  • Frequency: Most experts suggest using RLT devices 2-3 times a week for at least 10-15 minutes per session. Consistency is key to achieving optimal results.
  • Duration: It’s essential to be patient, as results may take several months to become noticeable. Experts recommend using RLT devices for a minimum of 3-6 months to assess their effectiveness fully.
  • Maintenance: Some people continue with maintenance sessions at a reduced frequency to sustain their hair health once they achieve their desired results. More longitudinal studies are necessary to study the long term effects on hair that’s been grown as a result of RLT.
red light therapy for hair growth

Safety Precautions

When using RLT devices, it’s important to follow safety precautions:

  • Eye Protection: Ensure to protect your eyes from the red light, as prolonged exposure to the eyes can be harmful. Some devices come with safety goggles or shields for this purpose.
  • Skin Sensitivity: If you have sensitive skin or a history of skin conditions, consult with a healthcare professional before starting RLT treatments.
  • Follow Instructions: Always follow the manufacturer’s instructions for your specific RLT device to ensure safe and effective use.
  • Consult a Professional: If you have any underlying medical conditions or concerns about using RLT, it’s advisable to consult with a dermatologist or healthcare provider before starting a treatment regimen.

Quick Guide: How to Use Red Light Therapy for Hair

Choosing the Right RLT Device

Here are some essential factors to consider when choosing an RLT device:

  • Wavelength: Pay attention to the specific wavelength of red light emitted by the device. Wavelengths in the range of 630 to 700 nanometers (nm) are often recommended for hair growth, specifically the wavelengths of 655 nm have shown to elongate anagen (growth) stage of hair. Research shows these wavelengths as optimal for stimulating hair follicles. Ensure that the device you choose falls within this range as otherwise it could result in the opposite effect (yes, hair loss).
  • Type of Device: Consider whether you prefer a handheld device for targeted treatment, a helmet or cap for full-scalp coverage, or a comb/brush for a combination of massage and therapy. The type of device you select should align with your convenience and lifestyle, your ability to commit to it regularly, and your treatment goals.
  • Power and Intensity: Different RLT devices offer varying levels of power and intensity. Higher-power devices may provide faster results, but you should use them with caution and according to manufacturer recommendations to avoid overexposure.
  • Ease of Use: Evaluate how user-friendly the device is. Look for features like timers, automatic shut-off, and adjustable settings that make it convenient to incorporate RLT into your routine.
  • Safety Features: Ensure that the device has built-in safety features such as eye protection mechanisms or shields to prevent accidental exposure to the eyes. Safety should always be a top priority.
  • Device Size and Portability: Consider the size and portability of the device. If you plan to use it while travelling, a compact and portable device may be more suitable.
  • Cost and Budget: RLT devices come in a range of price points. Determine your budget and explore options that provide the features and specifications you need without overspending.
  • Reviews and Ratings: Research customer reviews and ratings for the specific device you are considering. Real-world user experiences can provide valuable insights into the device’s effectiveness and reliability.
  • Brand Reputation: Opt for reputable brands with known for quality and reliability. Established brands often invest in research and development to create effective RLT devices.
  • Consultation with a Professional: If you have specific hair or scalp concerns, consider consulting with a dermatologist or healthcare professional before making a choice. They can offer guidance based on your individual needs.

Remember that the right RLT device for you may depend on your unique circumstances and preferences. Taking the time to research and choose wisely can help you make the most of the benefits that this treatment has to offer for hair growth and scalp health.

Integrating RLT into your hair care ritual:

Integrating Red Light Therapy (RLT) into your existing hair care routine can elevate the results you are already seeing from other treatments.

Consistency is key, so establish a regular schedule that works for you: using 2-3 times a week is more than a good start. Over time, you can adjust the frequency based on your progress and goals. Set a timer for the recommended treatment duration, which is typically 10 to 15 minutes per session.

Starting with shorter sessions and gradually increasing the time is advisable, especially if you are new to RLT. After each session, there’s no need to rinse or wash your hair. You can continue with your regular hair care routine if desired.

  • Scalp Massage: Gentle scalp massages can help improve blood circulation and enhance the effects of RLT. You can use your fingertips or a specialised scalp massager.
  • Healthy Diet: Maintain a balanced diet rich in nutrients that support hair health. Include foods high in vitamins, minerals, and proteins.
  • Proper Hair Care: Use mild and nourishing hair care products that suit your hair type. Avoid excessive heat styling and harsh chemicals.
  • Stress Management: High stress levels can contribute to hair loss. Practice stress-reduction techniques such as yoga, meditation, or mindfulness.
  • Consult a Professional: If you have specific hair or scalp concerns, consider consulting with a dermatologist or trichologist. They can provide personalised guidance and recommendations.

Precautions and Potential Side Effects

While Red Light Therapy (RLT) is generally considered safe, there are specific situations in which you should exercise caution or avoid RLT for hair:

  • Eye Conditions: If you have certain eye conditions or are taking medications that make your eyes sensitive to light, avoid using RLT devices that emit red light near the eyes. Protect your eyes with appropriate eyewear or consult with a healthcare professional.
  • Pregnancy: If you’re pregnant, you should consult with your healthcare provider before starting any new therapy, including RLT. While there is no conclusive evidence suggesting harm, it’s essential to prioritise safety during pregnancy.
  • Skin Sensitivity: If you have a history of skin conditions, allergies, or hypersensitivity to light, consult with a dermatologist or healthcare professional before using RLT. They can assess whether RLT is suitable for your skin type.
  • Photosensitivity: Some medications and substances can make the skin more sensitive to light. If you are taking such medications or have concerns about photosensitivity, seek medical advice before RLT.
  • Underlying Health Conditions: If you have an underlying health condition, especially those affecting the skin or eyes, you should consult with a healthcare provider before RLT. Your medical history can help determine whether RLT is appropriate for you.

Possible Side Effects and How to Mitigate Them

While RLT is generally well-tolerated, some people may experience mild side effects. Here are potential side effects and ways to mitigate them:

  • Skin Irritation: Some people may experience mild skin irritation or redness after RLT sessions. To mitigate this, ensure your skin is clean and free of irritants before treatment. If irritation persists, reduce the treatment time or frequency.
  • Eye Discomfort: If you experience eye discomfort or strain during RLT, ensure you are wearing appropriate eye protection, such as goggles or shields. Proper eye protection is crucial to prevent direct exposure to the red light.
  • Overexposure: Avoid overusing RLT devices or using them for longer durations than recommended. Overexposure can lead to adverse effects. Follow the manufacturer’s guidelines for treatment time and frequency.
  • Dryness or Sensitivity: Some people may notice dryness or sensitivity of the skin. Ensure you use a mild moisturiser if needed and maintain good skin care practices.
  • Consult a Professional: If you experience persistent or severe side effects, consult with a healthcare professional or dermatologist. They can provide guidance on adjusting your RLT routine or addressing any concerns.

Hair Growth Promoting Effects of 650 nm Red Light Stimulation on Human Hair Follicles and Study of Its Mechanisms via RNA Sequencing Transcriptome Analysis, (1)

Mitochondrial signal transduction in accelerated wound and retinal healing by near-infrared light therapy, (2)

The growth of human scalp hair mediated by visible red light laser and LED sources in males, (3)


Derma roller for hair growth: The Guide


Leave a Comment