Humble dry-heat saunas have been ubiquitous in country clubs and gyms across the U.S. since the free-spirited 70’s. But unlike amenities such as Vichy showers and Watsu pools, the cedar-lined rooms have become so unhip that some places now use them for towel storage. However, ahead-of-the-curve beauty insiders are once again embracing the age-gold treatment, thanks to its no-appointment-required accessibility and the immediate, just-off-the-slopes glow they get from a single session.

Dubbed ‘the poor man’s apothecary’ in an old Finnish proverb, saunas have been used in Nordic countries for more than 2,000 years for relaxation and cleansing, and as a place to give birth or ‘boil’ disease from the blood. Now, myriad medical studies suggest sauna enthusiasts have been onto something all along. When heat elevates the skin’s surface temperature, capillaries become dilated, blood flow to the skin increases, and sweat glands go into overdrive.

Although the circulation boost isn’t recommended for those with certain heart problems or heat-aggravated conditions such as rosacea or broken capillaries, researches have found that regular trips to the sauna can actually improve heart function in people with cardiovascular risk factors. And a nightly sauna session could postpone Ambien refills: In a study published in the research journal sleep, experts at New York Hospital recommend spiking body temperature 90 minutes before bedtime. The subsequent cooling, they propose, could help you fall asleep faster.