Contrast Therapy: What Alternating Sauna Heat and Cold Plunges Does for Your Body
The practice of cycling between heating and cooling the body has been practiced for thousands of years with the earliest evidence being Native Americans in their sweat lodges and cold river plunges and Northern Europeans in their traditional saunas and snow bathing.
Today this practice is called contrast therapy and is practiced by millions of people around the world typically with home saunas and cold plunge tubs.
This article takes an honest look at what the latest research says, how to do it well, and a few important caveats.
What Contrast Therapy Is
Contrast therapy is the deliberate alternation between heat exposure and cold exposure in a single session. A common pattern is 10 to 30 minutes of heat followed by 1 to 3 minutes of cold, repeated for two cycles.
The main shared underlying function between these two practices is vascular:
~ Heat causes blood vessels to dilate (vasodilation) which increases circulation, movement of heat through the body, core body temperature, and activates heat shock proteins.
~ Cold causes blood vessels to constrict (vasoconstriction) which decreases circulation, movement of heat through the body, core body temperature, and activates cold shock proteins.
As we always do at High Tech Health, it’s worth being precise here: much of the direct research on contrast therapy is still limited and often uses small samples. A great deal of what we know comes from studying heat alone and cold alone, each of which has a substantial evidence base, and reasoning about what happens when you combine them.
So many of the current claims out there are still reasonable inferences and I’ll flag where the evidence is genuinely strong versus where it’s still emerging.
The Heat Half: Sauna Therapy
The cardiovascular benefits for sauna bathing is one of the better supported findings in the heat therapy literature. One of the landmark studies in this regard is the Finnish prospective study that followed more than 2,000 men for roughly two decades and found that frequent sauna users had a significantly lower risk of fatal cardiovascular events than infrequent users. (1)
Heat exposure, through either a traditional sauna or far infrared sauna (2), raises core body temperature about 1.5 – 3 degrees F and triggers the production and release of heat shock proteins which are molecular chaperones that help repair and protect cells under stress and build future resilience.
One note specific to far infrared saunas, they work mainly by warming the body directly rather than superheating the air around you. The thermal load is ultimately the same but much more comfortable, which for many people translates to better tolerance, longer sessions, and most importantly more consistency, which is what actually drives long term benefits.
The Cold Half
Cold water immersion delivers a sharp, controlled stress that the body adapts to over time, which is a process called hormesis. The most reliable benefits center around reduction of inflammation, boosting mood, enhancing alertness, and building resilience to stress.
Cold exposure decreases core body temperature, triggers the production and release of cold shock proteins (which act similarly but also uniquely to heat shock proteins), and produces a measurable surge in norepinephrine and dopamine. Some research has even reported dopamine increases of well over 200 percent following cold water immersion, which helps explain the clear headed, almost euphoric “high” people describe after a plunge. (3) Repeatedly choosing to enter the cold and breathing through the initial shock also appears to train the autonomic nervous system, building tolerance to acute stress that can carry over into your daily life.
What Combining Them May Add
Here’s where the picture gets more nuanced and the honest answer is “promising, not proven.”
The strongest theoretical case for contrast therapy is the vascular mechanisms described above, plus the nervous system effect of toggling between the parasympathetic calm of heat and the sympathetic activation of cold. A small 2022 study of 30 men who alternated sauna heat with brief cold immersion found a significant drop in cortisol after sessions, though notably, that study had no control group, which limits how much weight we can put on it. (4)
What we can say with more confidence is that many people find the combination genuinely restorative, both physically and mentally, and the ritual itself promotes adherence to a consistent wellness practice. Those are real benefits even where the mechanistic data is still catching up.
The One Main Caveat That Actually Matters: Timing Around Strength Training
This is the detail most contrast therapy content skips, and it’s important enough that it could change when you cold plunge.
If your goal is building muscle, cold water immersion immediately after resistance training appears to blunt the gains. A well-cited 2019 study found that 15 minutes of cold-water immersion at 10°C after lifting attenuated muscle fiber growth (though, interestingly, not maximal strength) likely by dampening the very inflammatory and anabolic signaling that drives hypertrophy (the enlargement of an organ or tissue caused by an increase in the size of its existing cells). (5)
A 2024 systematic review and meta-analysis reached a similar conclusion: post workout cold immersion doesn’t eliminate muscle gains, but it does appear to reduce them by a small to meaningful margin. (6)
The practical takeaway is simple: the inflammatory response after lifting is part of how muscle grows, and cold suppresses it. So if you’re chasing hypertrophy, separate your cold plunge from your strength session by several hours, or save contrast therapy for rest days. If you’re doing endurance work, or your goal is general recovery and how you feel rather than maximizing muscle size, this concern largely doesn’t apply.
A Simple Protocol to Start
If you’re new to contrast therapy, gentle and consistent beats extreme and sporadic:
- Warm up first. Begin with 10–15 minutes in your sauna until you’re sweating comfortably.
- Brief cold. Move to a cold plunge or cold shower for 1–3 minutes. You don’t need ice bath extremes to get a vascular response. Water temp in the 50s°F is plenty for most people starting out.
- Repeat. Cycle back to heat for 10-15 minutes and repeat for 2 rounds total.
- Mind your finish. Ending on cold tends to leave you alert and energized which is great for a morning session. Ending on heat (or skipping the final plunge) is gentler before bed and supports the wind down toward sleep.
Hydrate well throughout, and listen to your body rather than pushing through dizziness or distress.
Who Should Be Cautious
Contrast therapy applies beneficial stress to your cardiovascular and nervous systems. But if you have heart disease, high or low blood pressure, are pregnant, nursing, or have any chronic medical condition, talk to your physician before starting, especially before adding the cold component which causes an acute spike in heart rate and blood pressure. Ease into both the heat and the cold gradually rather than jumping to the extremes.
The Bottom Line
Contrast therapy pairs two practices with strong individual track records: sauna heat for cardiovascular health, cellular resilience, and immune support, and cold immersion for mood, alertness, and stress tolerance. The combination is mechanistically sensible and, for many, deeply restorative, even if the research on contrast therapy as a distinct protocol is still maturing. Approach it consistently, time your cold exposure thoughtfully around strength training, and respect the real cardiovascular stress involved, and it can become one of the more rewarding rituals in your wellness routine.
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References
- Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Intern Med. 2015 Apr;175(4):542-8. doi: 10.1001/jamainternmed.2014.8187. PMID: 25705824.
- Vatansever F, Hamblin MR. Far infrared radiation (FIR): its biological effects and medical applications. Photonics Lasers Med. 2012 Nov 1;4:255-266. doi: 10.1515/plm-2012-0034. PMID: 23833705; PMCID: PMC3699878.
- Srámek P, Simecková M, Janský L, Savlíková J, Vybíral S. Human physiological responses to immersion into water of different temperatures. Eur J Appl Physiol. 2000 Mar;81(5):436-42. doi: 10.1007/s004210050065. PMID: 10751106.
- Podstawski R, Borysławski K, Pomianowski A, Krystkiewicz W, Żurek P. Endocrine Effects of Repeated Hot Thermal Stress and Cold Water Immersion in Young Adult Men. Am J Mens Health. 2021 Mar-Apr;15(2):15579883211008339. doi: 10.1177/15579883211008339. PMID: 33845653; PMCID: PMC8047510.
- Fyfe JJ, Broatch JR, Trewin AJ, Hanson ED, Argus CK, Garnham AP, Halson SL, Polman RC, Bishop DJ, Petersen AC. Cold water immersion attenuates anabolic signaling and skeletal muscle fiber hypertrophy, but not strength gain, following whole-body resistance training. J Appl Physiol (1985). 2019 Nov 1;127(5):1403-1418. doi: 10.1152/japplphysiol.00127.2019. Epub 2019 Sep 12. PMID: 31513450.
- Piñero A, Burke R, Augustin F, Mohan AE, DeJesus K, Sapuppo M, Weisenthal M, Coleman M, Androulakis‐Korakakis P, Grgic J, Swinton PA, Schoenfeld BJ. Throwing cold water on muscle growth: A systematic review with meta‐analysis of the effects of postexercise cold water immersion on resistance training‐induced hypertrophy. Eur J Sport Sci. 2024 Feb 5;24(2):177–89. doi: 10.1002/ejsc.12074. PMCID: PMC11235606.
