Many large saunas are not effective at focusing the available infrared energy at the body. This is particularly apparent when you lie down, which is the reason many people buy a large sauna. Happily the four-person Therasauna is the exception to the rule.

Remember that infrared is light, and it behaves like light. Surface temperature and proximity to the body are vital. Surfaces that are further away have to be hotter than those closer or the infrared does not reach you. Similarly, the heater surface itself must be oriented towards the body or it does no good. Light does not bend to find you. So, for example, those large carbon saunas with the panels going to the ceiling waste most of the infrared into the cabin air since the heater surface is much higher than the body itself. The infrared comes off of the surface in a straight line -- and misses the body. This is basic science that cannot be overcome with marketing hype.

Additionally, TheraSauna holds a proprietary patent that reduces voltage to the infrared emitters as the sauna cabin reaches the specified temperature. This means that the emitters never turn off during the sauna session, but rather cool down to deliver the longer far-infrared rays rather than having to shut off completely (as with ALL other infrared saunas, in spite of their claims). The effect is a tremendous increase in the amount of far-infrared produced during the sauna session.