Saunas and sleep might sound like a combination that came together in a sentence by accident, but they actually make for an unlikely match. More specifically, it is infrared saunas that can significantly improve your sleep quality on several different levels.
But first things first…
What is Infrared Sauna?
Instead of simply heating the air around you, as do regular saunas, infrared saunas employ infrared waves, which are longer, go through your skin and reach your inner environment, warming your insides before warming the outsides.
This way, infrared saunas provide the benefits of regular saunas at a lower temperature, largely sparing you the exercise of endurance that sitting in this super hot, stifling air usually entails. In fact, you even tend to sweat more in infrared saunas.
Benefits for Sleep
Naturally, saunas raise your our temperature significantly, which should at first glance go against sleep, which starts to settle in once the our body starts to naturally cool down. However, a sharp increase in our temperature in a sauna entails a sharp decrease afterwards. And since it’s the decrease in body temperature that the body associates with sleep, that heightened process of cooling down after a sauna primes the body for sleep.
Moreover, since infrared saunas warm us up o the inside, they loosen our muscle better and provide relief from muscle soreness and pain. And pain is one of sleep’s arch-nemeses.
In a study on infrared sauna’s effects on recovery from strength and endurance training sessions in men, the “deep penetration of infrared heat (approximately 3-4 cm into fat tissue and neuromuscular system) with mild temperature (35-50°C), and light humidity” appeared “favorable for the neuromuscular system to recover.” 
Another study explored infrared sauna as a potential remedy for rheumatoid arthritis over a 4-week period and came to positive findings. At the end of the study, the infrared sauna therapy was well tolerated, reducing pain, stiffness, and fatigue in a “statistically significant” manner, with no adverse effects. 
Speaking of sleep’s arch-nemeses, anecdotal evidence suggests people tend to find saunas to be a source of stress relief, and it’s only natural to assume that infrared saunas, which provide a more comfortable and relaxing experience, only improve on that.
Considering that infrared saunas have practically no side effects, especially for relatively healthy individuals, infrared saunas are a no-lose potential remedy for sleep issues.
1- Mero et al, Effects of far-infrared sauna bathing on recovery from strength and endurance training sessions in men, Springerplus 2015 Jul 7;4:321, Times Cited = 30
2- Oosterveld et al, Infrared sauna in patients with rheumatoid arthritis and ankylosing spondylitis. A pilot study showing good tolerance, short-term improvement of pain and stiffness, and a trend towards long-term beneficial effects, Clin Rheumatol 2009 Jan;28(1):29-34, Impact Factor = 2.042; Times Cited = 84