Updated in 2026 with real-world spectrometer measurements of Near Infrared output
Are you researching infrared saunas and finding yourself tangled in terms like far, mid, near, and full spectrum? You’re not alone. With bold marketing claims everywhere, it’s easy to wonder: what actually matters — and is a so‑called “full spectrum” infrared sauna really worth paying thousands more for?
At Sun Stream Saunas, we’ve always focused on separating real science from marketing hype. In this updated article, we explain what each infrared wavelength does (and doesn’t do), and we now include direct spectrometer testing that reveals a major flaw in how Near Infrared (NIR) is delivered in most full spectrum saunas.
Understanding Near, Mid and Far Infrared.
Infrared radiation is divided into three segments based on wavelength length:
- Near Infrared (NIR / IR‑A): 780–1400 nm
- Mid Infrared (MIR / IR‑B): 1400–3000 nm
- Far Infrared (FIR / IR‑C): 3000 nm–1 mm
Far Infrared is by far the largest portion of the infrared spectrum and is the primary wavelength responsible for the deep, penetrating heat we associate with sauna bathing.
Infrared light is naturally emitted by the sun and makes life on Earth possible. When infrared light strikes the human body, it is either absorbed, reflected, or transmitted. Only absorbed radiant energy generates heat — and heat is the fundamental purpose of a sauna.
Far Infrared (FIR): The Foundation of Effective Sauna Therapy
Far Infrared is invisible to the naked eye but provides a deeply penetrating heat similar to the warmth felt from the sun or an open fire. FIR has been safely used in infrared saunas for decades and is highly absorbed by the water content in skin and tissue. This absorption heats the body efficiently, stimulates circulation, raises core temperature, and promotes detoxification through sweat.
Why FIR Works Best in Saunas
- Human skin is approximately 80% water
- FIR has a high absorption rate in water
- FIR penetrates the skin (1–4 mm) and heats tissue via conduction
This absorbed heat raises core temperature, stimulates circulation, boosts immune response, and induces a deep detoxifying sweat — the primary objective of sauna use.
Carbon and ceramic infrared heaters produce the vast majority of their output in the FIR range, making them ideal for whole‑body radiant heat therapy.
Key takeaway: Far Infrared is the most effective wavelength for heating the human body and delivering authentic sauna benefits.
Mid Infrared (MIR): Minimal Benefit, Minimal Evidence
Mid Infrared occupies a very small portion of the infrared spectrum (1.4–3.0 microns). Outside of marketing claims from certain “full spectrum” sauna manufacturers, there is very little scientific literature demonstrating unique or meaningful health benefits from MIR exposure.
While MIR generates some heat, its absorption rate is lower than FIR, making it less effective for sauna applications.
Sun Stream’s ultra‑low EMF nano‑carbon heaters naturally emit FIR with:
- ~70% of output between 5–15 microns
- ~90% of output between 1–20 microns
This means our heaters already encompass the MIR range without the need for additional or hazardous components.
Near Infrared (NIR): Therapy vs Reality
Near Infrared (NIR) behaves differently from FIR and MIR. It passes through tissue with minimal heat generation, and its effects are primarily biochemical rather than thermal. Over the past decades, research into Photobiomodulation Therapy (PBMT) or Low-Level Light Therapy (LLLT) has shown that NIR can influence cellular energy production and healing — but only when delivered under controlled conditions using lasers or LEDs at precise wavelengths, intensity, and proximity to the skin.
Photobiomodulation Therapy (PBMT)
Since the 1960s, there is decades of research and now over 10,000 published studies on the therapeutic benefits of NIR and Red light which is known as Photobiomodulation Therapy (PBMT) or Low Level Light Therapy (LLLT) in the medical literature.
All PBMT/LLLT research has used either lasers or led sources of Red and NIR light. Single or dual frequencies of wavelengths in the visible Red 600nm range or invisible NIR in the 800nm range are the specific frequencies often used in the research. The research has discovered that our cells’ chromophores (light receptors) respond to a high intensity of a single or dual frequency in the 600nm or 800nm ranges.
NEW: Spectrometer Testing Reveals the Problem With “Full Spectrum” Sauna NIR
To cut through speculation, we conducted real‑world spectrometer testing on Near Infrared emitters used in full spectrum infrared saunas.
Watch the Test
What the Measurements Show
- At just a few inches away, NIR output measured less than ~1 mW/cm²
- In actual sauna use, the body is typically 2–3 feet away from these emitters
- At that distance, effective NIR delivery becomes negligible
This is orders of magnitude below the irradiance levels used in PBMT research and clinical light‑therapy devices.
In simple terms: the Near Infrared in most if not all full spectrum saunas is far too weak — at realistic distances — to deliver therapeutic light doses.
Full Spectrum Infrared Saunas: Marketing Vs Science
Some sauna companies use quartz halogen tube heaters or incandescent bulbs that emit visible light, near infrared, mid infrared, and far infrared. Unlike PBMT devices, these heaters cannot deliver controlled, high-intensity NIR to the skin without risk of burns due to extreme surface temperatures and the necessary distance for safe use.
Extended exposure to broad-spectrum NIR has been associated with skin photoaging, particularly in industrial settings where workers are exposed to high heat for prolonged periods. These heaters can also emit substantial EMF and ELF fields, sometimes exceeding advertised “low EMF” claims.
- Near Infrared & Full Spectrum Sauna Dangers
- White Paper – A Look At The Science and Safety of Shortwave (NIR) Heat
Halogen Heater Hazards
Quartz halogen heaters and traditional heat lamp bulbs have entered the infrared sauna market to capitalize on the popularity of NIR and Red Light Therapy. Advocates often claim that these devices can deliver the same benefits as PBMT/LLLT studies using lasers or LEDs. In reality, the light produced differs significantly from research-based NIR:
- PBMT delivers light at a precise, single wavelength and intensity for a controlled duration.
- Saunas using halogen or incandescent lamps emit broad, uncontrolled spectra, not the narrow therapeutic wavelengths required.
- Due to extreme heat, users cannot safely position themselves close enough to achieve effective NIR dosing.
Skin and Health Risks
Mounting heat lamps on sauna walls introduces multiple potential hazards. Excessive IR-A exposure can contribute to photoaging, similar to UV radiation, and research recommends sunscreen protection in high-exposure environments. EMF and ELF emissions from halogen tubes can reach up to 12–20 mG and over 300 V/m, despite marketing claims of low EMF. The glass bulbs themselves reach extremely high surface temperatures (~4000°F) and primarily heat the surrounding air rather than the body. Much of the energy emitted is mid-infrared or visible light, not therapeutic NIR, meaning these saunas fail to provide effective photobiomodulation.
Why NIR Saunas Fail
In essence, “Near Infrared Saunas” are a contradiction. NIR has low absorptivity and high reflectivity in skin, and effective therapy requires precise wavelength, intensity, and proximity. Halogen and incandescent devices cannot safely meet these requirements. In contrast, LED-based NIR devices deliver specific therapeutic wavelengths safely and can be placed near or directly on the skin to ensure effective energy delivery.
Conclusion
The primary purpose of a sauna is to heat the body, raise core temperature, and promote sweating. Far Infrared achieves this safely and efficiently. Near Infrared can be beneficial when delivered correctly, but most full spectrum saunas fail to provide therapeutic doses due to insufficient intensity, unsafe heat sources, and excessive distance.
Consumers should distinguish between heat therapy and light therapy to ensure the intended benefits are achieved.
For supporting evidence please read the following blog posts from infrared sauna experts Matt Justice and Alex Fergus:
Sun Stream’s Evidence-Based Solution
Sun Stream has developed ROJO Red & Near Infrared LED panels that deliver clinically relevant doses at precise wavelengths — 630 nm / 660 nm (red) and 810 nm / 830 nm / 850 nm (NIR) — with low EMF, minimal flicker, and safe proximity to the skin.
For more information, visit our ROJO Red Light Therapy page or contact us for guidance on integrating light therapy with infrared sauna use.