Low Level Laser Therapy (LLLT) and Light Emitting Diodes (LED) in Treatment of  Hair Loss

​Low Level Laser (LLL) and Light Emitting Diodes (LED) stimulate hair follicles and are used in hair loss treatment. 

​Most of the studies on the effectiveness of LLLT and LED have been done for androgenetic alopecia. 

A helmet-like light device for the hair loss treatment

​The mechanism of action of LLLT and LED is similar, but LED treatment is milder due to the type of light it emits.
In studies of pain management and skin rejuvenation, LED and LLLT results were somewhat comparable (Heiskanen, 2018). The effectiveness of LED for the hair loss is even less studied than the effectiveness of LLLT. 
 
​Some devices that use combined LLLT and LED showed up to 37% improvement in hair growth. ​
The advantage of using LLLT and LED is that they are completely pain free and non-invasive. 
​
What LLLT and LED are
Effectiveness in Hair Loss Treatment
​What is the treatment like and what to expect 
LLLT and LED Summary. Pros and Cons. LLLT vs LED
References

What LLLT and LED are, mechanism of action 

LLLT stands for Low Level Laser Therapy 
Laser is a focused coherent light, the depth of penetration of which depends on the wavelength. Most studies investigating effects of LLLT on the hair growth have used wavelengths that range from 635 to 650 nm (Avci, 2014).
​
Mechanism of action
Arndt-Shultz law states that every substance with pharmaceutical, healing, or poisonous properties heals in small quantities, inhibits in moderate quantities, and kills in large quantities. Applied to the laser effect on hair, it means that large quantities of laser (high level) treatment leads to hair removal, while low level laser treatment leads to hair stimulation.
​
The skin and hair rejuvenating effects of LLL therapy are produced by a mechanism known as photobiomodulation.
​​Photobiomodulation stimulates fibroblast proliferation, collagen synthesis, growth factors, and extracellular matrix production by activating cellular mitochondrial respiratory pathways (Ablon, 2018).

A meta-analysis of 11 studies (Afifi, 2016) that included a total of 680 patients, consisting of 444 males and 236 females showed that after an LLLT treatment in cases with androgenetic alopecia:

• in nine out of 11 studies, assessing hair count/hair density there were statistically significant improvements in both males and females;
• in two out of four studies that also assessed hair thickness and strength, there was a significant improvement;
• overall patient satisfaction was positive.

​For a sample treatment regiment see the section Effectiveness of the Combination of LLLT and LED below.

There is also some evidence that LLLT may darken gray hair by increasing melanin production in the hair follicles. 

​Light Emitting Diodes emit non-coherent light that is much milder in its effects than laser is.
The skin and hair rejuvenating effects of LED therapy, just like those of low level laser, are also produced through photobiomodulation.

LLLT and LED Effectiveness in Hair Loss Treatment

Studies on Low Level Laser Therapy Effectiveness
​ 
A meta-analysis of 11 studies (Afifi, 2016) that included a total of 680 patients, consisting of 444 males and 236 females showed that after an LLLT treatment in cases with androgenetic alopecia:

• in nine out of 11 studies, assessing hair count/hair density there were statistically significant improvements in both males and females;
• in two out of four studies that also assessed hair thickness and strength, there was a significant improvement;
• overall patient satisfaction was positive.

​For a sample treatment regiment see the following section on the combined LLLT and LED therapy.
​
Another review of the medical literature shows that the FDA-cleared LLLT devices are both safe and effective in patients with Male Pattern Hair Loss and Female Pattern Hair Loss who did not respond to or were not tolerant to standard treatments (Zarei, 2016). Though the optimum wavelength, coherence and dosimetric parameters remain to be determined (Avci, 2014).

There is also some evidence that LLLT may darken gray hair by increasing melanin production in the hair follicles. ​

Studies on LED effectiveness
The analysis of the mechanisms of action of LED suggests that LED should also be effective.
​LED therapy, just like laser, makes use of emitting light of a certain wavelength. However, LED light is more dispersed, less focused than the light from LLLT. And so it is softer, less damaging to the tissue, and for that very reason it is also generally not as effective as LLLT. 
LED has been used for a long time for the muscle injury treatment and it is well studied in this application. There is also a growing body of evidence of LED effectiveness in mild skin rejuvenation. 
Its use in promoting hair growth is recent and only minimally studied. 

As of the time of this publication, there has been one study demonstrating effectiveness of the LED alone (without LLLT) on the proliferation of the human derma papilla cells and on the hair follicle growth. It was an in-vitro study (cultured cells in a tube, not on people). The study showed that the LED with the 660 nm wavelength was indeed effective and resulted in cell growth (Joo, 2017).
​There are no human studies on the LED alone effectiveness. 

Effectiveness of the Combination of LLLT and LED
​There are also studies demonstrating effectiveness of a combination LLLT-LED therapy for the the hair regrowth in androgenetic alopecia. 
This particular study used a combination LED red light and Low Level Laser (655 nm wavelength) to treat persons with androgenetic alopecia, used for 16 weeks, every other day (60 treatments total), for 25 minutes.
The device used was a bicycle-helmet like "TOPHAT655". 

• In men, after the 16-week treatment course, the average increase in the hair count of the group actively treated with the device was 35% (Lanzafame, 2013);
• In women, after the 16-week treatment course, the average increase in the hair count was 37% (Lanzafame, 2014).

It is, however, unclear whether any portion of that effect stems from the LED dispersed light in addition to the effects already achieved with the LLLT alone. ​​

How the Procedure is Performed. What to expect

Those treatments can be done in an office treatment or at home. There are many helmet-like products and brushes for at home use.
LLLT and LED treatments last between 20 and 60 minutes and if a helmet-like device is used, the treatment consists of placing one's head under a laser or LED emitting device. There is no pain or discomfort during the treatment. 
​
Typically, a device needs to be used every other day for six months to see the full results. The duration of use per session should not exceed that stated by the device manufacturer so that the laser dose is kept in the low, healing, range. 
​
At the beginning of the treatments there may be some hair shedding. Noticeable changes begin after 2 months of consistent use; it takes up to 6 months to see the final results. ​

LLLT/LED Summary, Pros and Cons

Advantages - non-invasive (no pain, no downtime), safe - no side effects, less expensive than more invasive methods.
Drawbacks - requires discipline and long-term use, not likely to have dramatic results. For those who want an at-home device, requires an upfront investment. Unlikely to be effective at advanced stages of hair loss (three to five year after the hair disappeared, there are typically no follicles left under the skin to stimulate).

LED vs LLLT
There are many more Low Level Laser devices on the market and they are more expensive. Their effectiveness in the hair loss treatment is also better studied. 
LED devices are more affordable. Despite the lack of studies, judging by the mechanism of action and effectiveness for other health issues, LED should be at least almost as effective as LLLT. 

To improve the overall results, especially for the androgenic alopecia, either of the two (LLLT/LED) can be combined with an additional non-invasive treatment, such as topical Minoxidil. 

References

Ablon G. Phototherapy with Light Emitting Diodes: Treating a Broad Range of Medical and Aesthetic Conditions in Dermatology. J Clin Aesthet Dermatol. 2018;11(2):21-27.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5843358/

Hamblin MR. Photobiomodulation for the management of alopecia: mechanisms of action, patient selection and perspectives. Clin Cosmet Investig Dermatol. 2019;12:669-678. Published 2019 Sep 6. doi:10.2147/CCID.S184979
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6737896/​

Heiskanen V, Hamblin MR. Photobiomodulation: lasers vs. light emitting diodes? [published correction appears in Photochem Photobiol Sci. 2018 Oct 31;18(1):259-259]. Photochem Photobiol Sci. 2018;17(8):1003-1017. doi:10.1039/c8pp90049c
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6091542/

​Joo HJ, Jeong KH, Kim JE, Kang H. Various Wavelengths of Light-Emitting Diode Light Regulate the Proliferation of Human Dermal Papilla Cells and Hair Follicles via Wnt/β-Catenin and the Extracellular Signal-Regulated Kinase Pathways. Annals of Dermatology. 2017;29(6):747-754. doi:10.5021/ad.2017.29.6.747.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5705357/ 

Kim W-S, Calderhead RG. Is light-emitting diode phototherapy (LED-LLLT) really effective? Laser Therapy. 2011;20(3):205-215. doi:10.5978/islsm.20.205. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799034/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799034/

Lanzafame RJ, Blanche RR, Bodian AB, Chiacchierini RP, Fernandez-Obregon A, Kazmirek ER. The growth of human scalp hair mediated by visible red light laser and LED sources in males. Lasers in Surgery and Medicine. 2013; Oct; 45(8):487-95. doi: 10.1002/lsm.22173
https://www.ncbi.nlm.nih.gov/pubmed/24078483 

Lanzafame RJ, Blanche RR, Chiacchierini RP, Kazmirek ER, Sklar JA. The growth of human scalp hair in females using visible red light laser and LED sources. Lasers in Surgery and Medicine. 2014;46(8):601-607. doi:10.1002/lsm.22277.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4265291/
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