Forget pricey sauna memberships—your bathtub might be the ultimate wellness hack. A new study out of the University of Oregon found that soaking in hot water beats both traditional and infrared saunas when it comes to boosting cardiovascular and immune health.
Researchers tested 20 healthy young adults in three heat sessions: a 45-minute hot bath at about 105°F, a traditional sauna with breaks, and a far infrared sauna. The results? Hot water immersion raised core body temperature nearly three times higher than the sauna sessions. This triggered greater heart activity—participants’ heart rates spiked by nearly 40 beats per minute in the tub, versus about 34 in a regular sauna and just 25 in the infrared version.
Better still, a hot soak dropped blood pressure significantly more than a sauna session, mirroring the effects of moderate exercise. Even the immune system got a lift: key immune cells that fight infection and disease increased for up to two days after the hot bath.
Why is the tub so powerful? Water transfers heat to the body far more efficiently than air, warming you evenly and making it harder for your body to cool itself off. Meanwhile, the actual temperatures inside saunas often fall short of what’s advertised, limiting the benefits.
So, if you’re looking for an easy, affordable way to support your heart and immune system, you might want to skip the fancy spa and turn on the tap instead. Just check with your doctor if you have health conditions that make heat risky.
For now, science suggests that a simple soak might be the healthiest excuse yet to carve out time for a long, hot bath—no sweat lodge required.