Let there be (Red) Light, please!

Heliotherapy, or the therapeutic use of natural sunlight, dates back over 3,500 years to all ancient civilisations.  The term combines helios (sun) and therapeia (healing).   Health benefits of sunlight  were  common knowledge and   sunbathing  was considered a remedy   for  ailments such as  skin discoloration including leucoderma, mood disorders etc.  In other words  rejuvenating effects of   of sunlight  were well understood.  

By  late 19th century, it was  known that ultraviolet light could kill  bacteria. Danish  physician Niels Ryberg Finsen developed an artificial ultraviolet light source  to treat skin diseases. In 1903  Finsen was awarded the  Nobel Prize in Physiology/Medicine. His citation reads:  "in recognition of his contribution to the treatment of diseases, especially lupus vulgaris , with concentrated light radiation, whereby he has opened a new avenue for medical science"  Lupus vulgaris,  a form of tuberculosis,   attacks the skin, especially on the face and neck.    Finsen  reasoned  that  focusing UV light selectively on the affected area  would  kill off the pathogen. (Incidentally it was later proved that   the lenses used in Fensen's Lamp filtered off most of the UV and it was  a photochemical reaction involving nascent oxygen that killed off the bacteria).   In any case Finsen's  technique had limited success    because    the process  was too  slow,  painful and  above all quite  expensive.  And then  antibiotics  arrived on the scene and shouldered the responsibility of annihilating bacteria. 

In the meanwhile heliotherapy moved from outdoors to indoors as  Phototherapy,    with focus on    blue light(400–470 nm) and  red light (620–750 nm).  Since 1950's Blue Light Therapy  has been in use  to treat  jaundice in new borns.   It was also  reported that  blue light could kill acne-causing bacteria (Cutibacterium acnes) and to some extent alleviate  oily skin.  Then came claims that  Red light could  stimulate  collagen growth and ease out wrinkles.  These whispers didnot draw much attention because scientists were not fully convinced.  Then   in  1960s,  while studying the cancerous effects if any, of red light on skin,  Hungarian scientist Endre Mester  made a rather  surprising observation: that  shaved  mice subjected to red light treatment sported luxuriant hair growth afterwards.  Soon  several studies reported  that  "red light plumps up skin features  and facilitates hair growth in human participants through an increase of collagen production."   Scientists suspect that  vasodilation is probably the root cause  for remarkable  dermatological effects of red light.   When NASA (National Aeronautics and Space Administration)  began experimenting with red light therapy on plant growth in space and also to help heal wounds in astronauts, the technique got a boost.  Soon Red Light Therapy received  acceptance under a new name   "Photobiomodulation"  and found a place in medical  courses.  Often, the terms  Photobiomodulation therapy and red light therapy are  used interchangeably, but there is  a slight  difference.  Red light therapy focuses primarily on visible wavelengths (around 630-670 nm),  whereas PBMT also includes  near-infrared light (up to 1070 nm).   

The initial  biological step underlying the hair growth and skin rejuvenation are the same and begins with the absorption  of red and near-infrared light (typically 600–850 nm)  by Cytochrome c Oxidase (CCO), a light-sensitive enzyme inside the cellular power plant   mitochondria.   On the skin  the light stimulates cells in the dermis layer  and  accelerates the synthesis of collagen, elastin, and hyaluronic acid to repair withered  tissue. Together, these molecular effects improve the skin structure and quality, increase elasticity and enhance a youthful look.  In the case of hair,  light targets dermal papilla which are   small, specialised structures at the base of the hair follicles.  The extra energy prolongs the anagen (active growth) phase, prompts resting follicles to regrow  and  prevents follicle shrinkage.  

However scientists are not fully convinced, because the Gold Standard of Randomized Controlled Trial has not been done .  Such a study stipulates  a series of  randomized, controlled experiments with two  groups  of people  of  the same range of characteristics (skin/hair , age, weight, race, sex, etc.) one group receiving  the RLT and the other none at all , everything else remaining the same.  The results then need to be analysed statistically to arrive at a firm conclusion.  Such a rigorous study  has not  been done yet. 

 TAILPIECE:

Hair and   Skin!!!   From the very beginning  cosmetic  industry has been eager  to encash on  the idea.  By 1990's   red light therapy for skin rejuvenation and wrinkle reduction was made available  for exclusive use in  professional clinics.   FDA  clearance  for the commercial sale of "similar" devices came  in 2000.  Now market is flooded  with   masks, wands, hand-held panels, laser caps, and  even full-body systems  facilitating  at home  beauty care routines.   Though these devices do not carry use  only after consultation with the doctor label, it is better to do so... 

REFERENCES:

1. The Health Benefits of Sunshine (and How Much You Need Per Day)

2. How Finsen's light cured lupus vulgaris

3.. Red light therapy: What the science says  By Hanae Armitage

4. The surprising science behind red-light therapy — and how it really works

5. What to Look for in Red Light Therapy: A Product Guide Backed by Science

6. Biological and Therapeutic Responses of Human Skin to Different Wavelengths of Light: A Comprehensive Review

7. Philips Skylight, designed to bring the feeling of daylight indoors