Article · Scalp & Hair Care
Laser Light and Hairs Grown in a Lab Dish: A 2010 Study
The short answer
A small 2010 lab study, reported in a Journal of the American Academy of Dermatology abstract, measured how hairs kept in a dish grew under two laser wavelengths; with one donor and no statistics shown, it can't tell us what happens on a scalp.
What did this study test?
According to the 2010 abstract, low-level laser therapy (LLLT) uses low-energy laser light. Both wavelengths in this study sit near the red end of visible light, which NASA puts at about 380–700 nm. The abstract notes earlier research on a 660 nm device in men. What hadn't been studied, the author writes, was how other laser doses affect hair growing outside the body.
According to the abstract, the study used hairs collected during scalp surgery, kept in a standard hair culture medium at 37°C. Laser hairs were randomly assigned to groups of 10, and 10 control hairs were chosen separately:
635 nm laser light
660 nm laser light
Both wavelengths, 2 minutes of each
An inactive control
The abstract reports that each group was exposed for 4 minutes a day. Each hair was measured from bulb to tip at the start and again on days 3, 7 and 10.
What did the researchers find?
The abstract reports this average growth after 10 days, by group (10 hairs per group, all from one donor):
635 nm: 697 µm (about 0.7 mm)
660 nm: 533 µm (about 0.5 mm)
Both wavelengths: 533 µm (about 0.5 mm)
Control: 432 µm (about 0.4 mm)
In this study, using both wavelengths ended level with 660 nm alone, according to the abstract. The abstract shows no statistical tests for these numbers.
Does this mean laser light helps hair grow on your scalp?
This study can't say. A few details matter when reading it:
One donor. The abstract describes hairs from a single donor. We don't know whether other people's hair would respond the same way.
A dish, not a scalp. The hairs grew outside the body for 10 days, according to the abstract.
Unclear control group. The abstract says the control hairs were collected at the start, yet it reports their growth through day 10.
Uneven groups. In the abstract, the control hairs were picked from a thicker range than the laser hairs.
Funding. The abstract lists commercial support from Lexington International.
What this means for you
The abstract doesn't include recommendations for readers.
Beyond the Study: If you have questions about thinning hair, a board-certified dermatologist can help you understand what may be behind your hair changes.
FAQs
Does red light therapy help hair growth?
This study tested red laser light on hairs in a lab dish. It can't say whether an LED panel, a mask or any home device helps hair on the scalp.
Can laser light help thinning hair in women?
This study can't answer that: no women took part.
For the full findings and methods, read the full publication: Evaluation of the activity of laser light doses compared to an inactive control dose on ex vivo hair growth.
Read the full publication → Leavitt M. Evaluation of the activity of laser light doses compared to an inactive control dose on ex vivo hair growth. J Am Acad Dermatol. 2010;62(3 Suppl 1):AB76. Abstract P2109. doi:10.1016/j.jaad.2009.11.319
Disclosure: Dr. Matt Leavitt, the study's author, is a Co-Founder of Xtressé.
This article is for education only and is not medical advice. Talk with your healthcare provider about your own hair and scalp health.
Key takeaways
- The hairs came from scalp surgery and were kept in a standard hair culture medium at 37°C.
- Laser hairs were randomly assigned to 635 nm light, 660 nm light or both wavelengths, and each hair was measured from bulb to tip on days 3, 7 and 10.
- Using both wavelengths ended level with 660 nm alone, at 533 µm (about 0.5 mm) of growth.
- The control hairs were picked from a thicker range than the laser hairs, so the groups were uneven.
- The abstract lists commercial support from Lexington International.
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