I sat in a 175°F sauna last month and had a thought you've probably had too: Is this actually doing anything?
I went to the literature. The answer is yes — and the numbers are bigger than I expected.
The Data
A landmark 2015 JAMA Internal Medicine study followed 2,315 Finnish men for 20 years. Here's what they found:
4-7 sauna sessions/week → 40% lower all-cause mortality
Cardiovascular death → cut by 50%
Sudden cardiac death → reduced 63%
Alzheimer's risk → 65% lower (2017 follow-up study)
Even 2-3 sessions/week still cut mortality by 24%
These numbers held up after adjusting for age, BMI, exercise, smoking, and income. The benefit was dose-dependent — more sessions = better outcomes. Sessions over 19 minutes outperformed shorter ones.
This isn't one lucky study. Laukkanen's team published follow-ups in Age and Ageing and BMC Medicine showing the same pattern across dementia, hypertension, and inflammation.
What's Happening In Your Body
Your body can't tell the difference between running and sitting in extreme heat. Both trigger real cardiovascular work:
Heat shock proteins (HSP70) ramp up — these refold damaged proteins and protect against neurodegeneration
Growth hormone spikes 2-3x acutely
BDNF increases — the same brain-growth protein that makes exercise protect cognition
Blood pressure drops over time as arterial compliance improves
Infrared vs. traditional? Both raise core temp and trigger the same pathways. Traditional has deeper evidence, but infrared works if that's what you have access to.
What To Do
Frequency: 4x/week (the dose that showed max benefit)
Duration: 20+ minutes (the data showed a clear cutoff at 19 min)
Temperature: 175-190°F traditional, or whatever gets you sweating hard in infrared
Don't skip electrolytes. You lose 0.5-1 liter of sweat per session. That's sodium, potassium, and magnesium walking out the door. I bring LMNT packets to every session and take 200mg of Thorne Magnesium Bisglycinate on sauna days.
Don't sauna within 2 hours of bed. Your body needs time to cool down before sleep. Late afternoon is the sweet spot.
Product Pick
If you don't have gym sauna access, a HigherDose Infrared Sauna Blanket is the most practical home option. It hits genuine thermal stress within 20 minutes, folds away when you're done, and costs a fraction of a built-in unit.
Quick Hit
Cold plunge after sauna? A 2022 study found the combo boosted norepinephrine and well-being more than either alone. Worth trying if you enjoy it — but the longevity data is for heat alone.
40% lower mortality from sitting in a hot room. Not a drug. Not a surgery. Heat. If you're optimizing for longevity and not using heat strategically, you're leaving one of the easiest wins on the table.
Got a sauna routine? Hit reply and tell me what's working.