Unlike the Far Infrared emitting carbon and ceramic heaters used in most Infrared saunas, some sauna companies use incandescent, halogen gas tube heaters and bulbs which emit Visible light, Near Infrared, Mid Infrared and Far Infrared.

The Problem with Near Infrared Saunas

Included in this group are the common ‘heat lamp’ bulbs, best known for food warming at fast food restaurants, for bathroom ceiling installations and which are commonly found in chicken coups to warm young chicks. These common and inexpensive bulbs have been used to create saunas and proponents of their use have inaccurately termed these ‘Near Infrared’ saunas.

While manufacturers of these bulbs, such as Sylvania and Philips, may label the bulbs ‘Near Infrared ‘ heat lamps, analysis of their spectral distribution curves shows that these bulbs emit the majority of their energy in the Mid Infrared range while emitting very little Near Infrared (perhaps 20%), very little Far Infrared and significant visible light. Additionally, the glass globes of these bulbs are dangerously hot (approx 4000F) and have a significant heating effect on the air. The heating effect of these so called ‘Near Infrared’ saunas is NOT due to their Near Infrared output. As discussed above, Near Infrared has a low absorption rate and a high reflective rate and does not generate much heat in our body. It would appear that users of the heat lamp saunas are warming their bodies with the less efficient Mid Infrared and by simply heating the air in the small canvas tents typically used for these saunas. Given that Near Infrared does not produce much heat in our bodies, we have always considered the term ‘Near Infrared’ sauna to be a contradiction of terms and the proponents of these saunas have added tremendous confusion to the Infrared sauna marketplace.

Full Spectrum Saunas | Hazards of Halogen Heaters

Also adding to the confusion in the marketplace are the so called ‘Full Spectrum’ saunas. A small handful of Infrared sauna companies have added quartz halogen tube heaters to their Far Infrared saunas and called these ‘Full Spectrum saunas’. The halogen tube heaters are used in many industrial drying applications and are common in outdoor patio heaters. They are much like the heat lamp bulbs in that they use a filament inside of a halogen gas filled enclosure. Like the heat lamp bulbs, these ‘Full Spectrum heaters’ emit across the full range of Infrared (Near, Mid and Far), are very hot on their surface and emit significant energy as visible light. Like the heat lamp bulbs, the halogen tubes are not focused on producing Far Infrared, the wavelengths which are understood by science to be most efficient for heating the human body.

Both the quartz halogen heaters and the common heat lamp bulbs have been introduced to the Infrared sauna market attempting to ride on the coat tails of the research on Near Infrared and Red light therapy. Since the 1960’s the therapeutic use of Near Infrared light and visible Red light have been extensively researched. Known as LLLT (Low Level Light Therapy) or Photobiomodulation Therapy (PBMT), researchers and practitioners have administered these frequencies of light with lasers and LED devices. There is even a department of ‘photomedicine’ associated with Harvard Medical School.

Proponents of the Full Spectrum and the Near Infrared heat lamp saunas will often cite the benefits achieved in the PBMT/LLLT studies and suggest that these same benefits can be achieved with their inexpensive tube and bulb heaters. However, the Near Infrared light energy delivered from the devices in these saunas has very little in common with those in the studies. PBMT administers the light at a specific, single wavelength, at a specific intensity and for a specific time, thus delivering a measured ‘dose’ of the light energy. The duration of PBMT is actually very short, usually only a few minutes whereas an Infrared sauna session is usually 30-45 minutes.

Mounting the heat lamp bulbs or halogen tube heaters on the wall of a sauna may be a very misguided product idea and present hazards to the skin. There is a significant body of research indicating that excessive Near Infrared (IR-A) exposure has a ‘photoaging’ effect on our skin much like that of UV. Some papers have suggested that sunscreens should protect against IR-A in addition to UV. Photoaging damage to the skin from Near Infrared is well known on the faces of career molten metal workers and on the arms of those working with large ovens (Baker’s Arm). While Near Infrared delivered at a single wavelength, for a short controlled duration has many therapeutic applications, the use of Near Infrared emitting tube heaters and bulbs in the Full Spectrum and Near Infrared saunas, perhaps for several days a week and for years on end appears to be a poorly contrived, hazardous option for a sauna.

References

The Preferred Wavelengths for Comfort Heating, Herschel Infrared Heaters
https://www.herschel-infrared.com/how-it-works/preferred-wavelengths-comfort-heating
Ceramicx Ireland Technical Report, Dr. Gerard McGranaghan, Institute of Technology Sligo
https://www.herschel-infrared-technology-center.com/wp-content/portal/whitepapers/CCII-00041-Preferred-wavelengths-for-Comfort-Heating.pdf
Peter Schroeder, Judith Haendeler, Jean Krutmann, The role of near infrared radiation in photoaging of the skin, Experimental Gerontology, Volume 43, Issue 7, July 2008, Pages 629-632, ISSN 0531-5565,
Soyun Cho, Mi Hee Shin, Yeon Kyung Kim, Jo-Eun Seo, Young Mee Lee, Chi-Hyun Park and Jin Ho Chung, Effects of Infrared Radiation and Heat on Human Skin Aging in vivo, Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 15–19;
Schroeder P, Calles C, Krutmann J. Prevention of infrared-A radiation mediated detrimental effects in human skin. Skin Therapy Letters. 2009 Jun;14(5):4-5.
The Other End of the Rainbow: Infrared and Skin Aton M. Holzer, MD and Craig A. Elmets, MD
J Invest Dermatol. 2010 Jun; 130(6): 1496–1499.