Yes — but only if it’s hot enough. A 2026 study out of Cardiff Metropolitan University found that a far-infrared sauna running at 65°C (149°F) for 45 minutes raised core body temperature by 1.4°C, close to what a traditional sauna does. Earlier studies at the more common infrared temperature of ~45°C (113°F) found no core temperature change at all. The deciding factor isn’t the technology. It’s the temperature.
“Infrared sauna isn’t a real sauna” is a complaint you’ll run into a lot if you spend any time in sauna forums or talk to people who grew up with a Finnish-style sauna. The core of the complaint is usually this: infrared doesn’t get hot enough to actually raise your core body temperature, so you’re just sitting in a warm box and sweating a little.
For a long time, nobody had a clean answer either way. That changed in 2026.
Where the “It’s Not a Real Sauna” Complaint Comes From
Traditional Finnish saunas run at 80–100°C (176–212°F). At that temperature, the air itself does most of the work — it transfers heat to your skin through convection, the same way a hot day makes you sweat, just faster and more intense. Decades of research confirm this reliably pushes core body temperature up by 1–2°C.
Infrared saunas work differently. Instead of heating the air, panels emit infrared light that gets absorbed directly by your skin and converted to heat. Most infrared saunas run at 45–60°C (113–140°F) — much cooler air, in theory doing the heating a different way.
The question that’s been sitting unanswered: does that different mechanism actually get the job done, or does it just feel warm without doing much?
What the 2026 Study Actually Found
Researchers at Cardiff Metropolitan University put 12 healthy adults into a far-infrared sauna at 65°C (149°F) for 45 minutes and tracked their rectal temperature — the standard, most reliable way to measure core body temperature in this kind of research.
Rectal temperature climbed from 37.3°C to 38.7°C — a rise of 1.4°C. It started showing up around the 20-minute mark and kept climbing through the full session. Heart rate went from 74 to 153 bpm. Participants sweated at a rate of 1.4 liters an hour.
The researchers compared this to what’s already known about traditional sauna and hot water immersion. The number lined up: 1.4°C sits right in the range those older, well-established methods typically produce.
| Study | Temperature | Duration | Core Temp Change |
|---|---|---|---|
| Reed et al., 2025 | ~45°C / 113°F | 45 min | 0.0°C (intestinal) |
| Atencio et al., 2025 | ~45°C / 113°F | 45 min | 0.0°C (rectal/intestinal) |
| Jenkins et al., 2026 | 65°C / 149°F | 45 min | +1.4°C (rectal) |
That table is really the whole story. Same general idea — sit in an infrared sauna for 45 minutes — but a 20°C gap in air temperature is the difference between “nothing measurable happened” and “your core temperature moved as much as a traditional sauna.”
Why Low Heat Doesn’t Do the Same Thing
Your body is constantly trying to get rid of extra heat — through blood flow to the skin, and through sweat evaporating off your skin. At lower infrared temperatures, your body can dump heat about as fast as the panels are adding it. Net result: your skin and muscles warm up, but the heat never really piles up deep inside you.
At 65°C, that balance breaks. The air is now hotter than your skin, sweat has a harder time evaporating because humidity inside the cabin climbs too, and heat starts building up faster than your body can shed it. That’s when it reaches your core.
Here’s the part worth being upfront about: the researchers themselves say they can’t fully separate two things happening at once — heat coming from the infrared panels directly, and heat coming from the air itself, which is now considerably hotter than a typical infrared session. In plain terms, we don’t know exactly how much of that 1.4°C is “infrared doing infrared things” versus “the room just being genuinely hot now.” Both are probably involved. The study wasn’t designed to untangle that, and it says so.
Does This Mean You Should Buy a High-Temperature Sauna?
Not automatically, and that’s worth saying clearly. This study answers one specific question — can infrared raise core temperature the way a traditional sauna does — and the answer is yes, at the right temperature. That’s not the same as saying every infrared sauna benefit depends on hitting 149°F.
Circulation, muscle relaxation, that calm feeling after a session — a lot of what people actually use infrared saunas for doesn’t require chasing a core-temperature spike. If that’s what you’re after, a standard 120–140°F session still does the job it’s always done.
Where this matters is if your specific goal is matching a traditional sauna’s physiological effect — the kind of heat stress linked to cardiovascular adaptation and heat acclimation research. For that, temperature is the lever that matters, and you’d want a unit that can actually get up near 149°F and hold it. Our high-temperature infrared sauna picks cover four models rated for 165–170°F, which clears this threshold on paper.
One thing worth flagging: the sauna used in this study was a commercial-grade Clearlight Sanctuary Pro unit, built with more powerful heaters than the standard residential Sanctuary line most home buyers get. Our own Clearlight review found the residential Sanctuary and Premier lines top out around 125–145°F — below the 149°F this study actually tested. If you specifically want the setup this research used, that’s a meaningfully different tier of hardware than a standard home unit.
The Part That’s Easy to Skip: Two People Couldn’t Finish
Higher heat isn’t free. Two of the twelve participants in this study stopped early — one at 40 minutes, one at 43 — because it was too uncomfortable to continue. By the end of the session, people rated the heat as “extremely hot” and “extremely uncomfortable.” Heart rate hit 153 bpm. Blood pressure dropped noticeably right after.
None of that is unusual for this kind of heat stress. It’s just a reminder that 149°F for 45 minutes is a real physiological event, not a spa upgrade with no trade-off.
Sauna manuals are consistent on this point: don’t let your core temperature climb past 103°F (39°C). Past that, you’re looking at dizziness, drowsiness, and in worse cases, fainting or an inability to recognize you need to get out. Pregnant women, and anyone with heart disease, diabetes, or blood pressure issues, should check with a doctor before pushing into high-heat sessions. Start lower, build up over a few sessions, and treat “I feel dizzy or unusually uncomfortable” as your signal to leave, not push through.
PRL Take: This isn’t us telling you to go buy the hottest sauna you can find. It’s one solid, peer-reviewed data point that finally answers a question the industry argued about for years without much evidence either way. Infrared sauna can raise your core body temperature to the same degree a traditional sauna does — that part is now backed by real numbers. Whether you need that effect depends entirely on what you’re using a sauna for in the first place.
FAQ
Can infrared sauna really raise your core body temperature?
Yes, at high enough temperatures. A 2026 study found a 1.4°C rise in core (rectal) temperature after 45 minutes at 65°C (149°F). Earlier research at the more typical infrared temperature of ~45°C found no core temperature change at all.
Why do some studies say infrared sauna doesn’t raise core temperature?
Those studies were run at lower temperatures, around 45°C (113°F) — the range most home infrared saunas actually use day to day. At that heat level, your body dissipates heat about as fast as it builds up, so it never really reaches your core.
What temperature does an infrared sauna need to hit to raise core temperature?
The one study that found a clear effect used 65°C (149°F) for 45 minutes. That’s meaningfully hotter than the 120–140°F most infrared saunas are used at day to day.
Is it safe to use an infrared sauna at 149°F?
It can be, but it’s a real heat stress event, not a casual session. In the study, two of twelve participants stopped early due to discomfort. Keep your core temperature under 103°F, build up gradually, and check with a doctor first if you’re pregnant or have a heart condition, diabetes, or blood pressure issues.
Sources
| Source | Used For | Last Checked |
|---|---|---|
| Jenkins et al., 2026, Experimental Physiology | Core study: 65°C/149°F, 45-min exposure, core temp and physiological data | September 2026 |
| Reed et al., 2025, Journal of Applied Physiology | Lower-temperature (~45°C) comparison, no core temperature change | September 2026 |
| Atencio et al., 2025, American Journal of Physiology | Lower-temperature (~45°C) comparison, no core temperature change | September 2026 |