The term "light therapy" covers a wide range of devices with very different mechanisms. If you're specifically looking to support vitamin D levels, most of what's marketed as "light therapy" won't help.
The main types of light therapy devices
SAD lamps: Emit bright white light (2,500–10,000 lux). Work through the eyes to support mood and wakefulness. No UV. No vitamin D synthesis. These are appropriate for light exposure during dark months but address a different mechanism than vitamin D.
Red light panels (photobiomodulation devices): Emit 630–850 nm wavelengths. Studied in relation to cellular energy, mitochondrial function, and tissue wellness. No UV. No vitamin D synthesis.
Broadband UVB lamps: Emit UVB across the full 280–315 nm range, often with some UVA. Effective for vitamin D synthesis but less targeted than narrowband.
Narrowband UVB lamps: Emit specifically in the 311–313 nm range. The clinical standard for phototherapy. Most efficient for vitamin D synthesis with the most controlled exposure profile.
Full-spectrum + multi-spectrum devices: Combine multiple wavelengths (UVB + red + NIR). Designed to restore multiple biological inputs in a single session.
For vitamin D specifically
The only category that supports vitamin D synthesis is narrowband UVB. Any device that doesn't emit UV in the 280–315 nm range cannot trigger the photochemical conversion of 7-dehydrocholesterol — the foundation of cutaneous vitamin D production. (Holick MF. Vitamin D deficiency. N Engl J Med. 2007.)
Why narrowband outperforms broadband for this purpose
Broadband UVB covers a wider range but includes wavelengths below 295 nm that contribute to erythema (skin reddening) without meaningfully adding to vitamin D synthesis. Narrowband UVB concentrates in the 311–313 nm range — the peak of vitamin D photosynthesis efficiency — with a more controlled exposure profile.
The case for a multi-spectrum device
If the goal is to address the full range of what indoor living removes — vitamin D synthesis, cellular energy support, and infrared tissue wellness — a device that combines UVB narrowband, red light, and NIR is more complete than any single-spectrum option. This is the design logic behind the Mitolux BTS2.
Disclaimer: Mitolux is intended for general wellness and self-care use. Individual experiences vary. This content is for informational purposes only and does not constitute medical advice. Mitolux is not intended to diagnose, treat, cure, or prevent any disease. Use only as directed. Consult a qualified healthcare professional before use if you have a medical condition, are pregnant, or take medications that increase light sensitivity.