Sauna + Cold Water Bath: Really More Healthy? Scientific Analysis

Jumping into the cold pool after a sauna - this seemingly extreme contrast is actually a centuries-old Nordic tradition. Finns often go into snow or ice lakes after a sauna, and Sweden and our country also have similar alternating hot and cold traditions.

However, this habit really came into the public eye only in recent years. With the promotion by health bloggers and the support of a large number of research results, "sauna + cold bath" quickly became a global topic.

But is this combination really healthier than just a sauna alone? What are the clear scientific supports? And what are the rumors spread on social media that should be believed?

What is "Contrast Therapy"?

Contrast Therapy, also known as "Cold and Hot Alternation Therapy", refers to a healthy practice where one is consciously exposed alternately to a hot environment (such as a sauna or hot bath) and a cold environment (such as cold water immersion, ice water bath, or cold mud bath).

The core difference between this therapy and simply taking a sauna or a cold bath alone lies in the fact that the alternating cold and hot stimulation triggers a more intense physiological response, and is believed to have an "additive effect", meaning that 1 + 1 > 2.

Common forms of contrast therapy	Heat source temperature / Cold source temperature
Sauna + Cold Water Pool	80–100°C / 10–15°C
Sauna + Cold Water Soaking (Soaking with Steam)	80–100°C / Room temperature liquid
Hot Bath + Cold Bath	38–40°C / 14–15°C
Sauna + Ice Bath	80–100°C / 8–12°C

What Happened To The Body?

To understand the effect of contrast therapy, we need to first examine what heat and cold do to the body separately.

Heat: The Effects of Sauna

The high-temperature environment of a sauna triggers a series of physiological reactions, similar to moderate aerobic exercise:

• Vascular dilation (vasodilation), increased heart rate, and accelerated peripheral blood circulation
• Activation of heat shock proteins (Heat Shock Proteins), which help cells repair and counteract oxidative stress
• Release of endorphins and dopamine, leading to relaxation of the mind, enhancement of physical and emotional well-being, and reduction of pain
• Decrease in cortisol (stress hormone) levels, which helps in resisting chronic stress

A 20-year large-scale study in Finland (Laukkanen 2019) shows that those who sauna 4-7 times per week have a 50% reduction in the risk of heart disease.

Cold: The Effects of Cold Bathing

The potential benefits of a cold bath can be further enhanced. It is a strong stimulus to the nervous and endocrine systems:

• Vasodilation (vasoconstriction), with blood redistributed from the periphery to the internal organs
• Continuous increase in dopamine, studies have shown that in 14°C cold water baths, dopamine can increase by approximately 250%
• Immunoglobulins (IgG, IgA, IgM) increase, experiments have shown that those who undergo 30 days of cold bathing have a reduction of about 29% in sick leave
• Brown fat activation, promoting an increase in basal metabolic rate

Alternating hot and cold temperatures

The most unique mechanism of contrast therapy operates through its "vascular pumping effect" which results from using alternating hot and cold temperatures. The process of expanding and contracting blood vessels and digestive organs functions as an exercise that helps blood vessels and digestive systems remove metabolic waste while receiving fresh oxygen and nutrients. Long-term use can improve vascular elasticity.

What Are The Scientifically Proven Health Benefits?

Cardiovascular Health

This is the most well-documented benefit. The friendly effects of saunas on the cardiovascular system have been demonstrated quite extensively. Intermittent cold exposure has been shown to be more effective than conventional therapy in providing further training for blood vessels, reducing arteriosclerosis, and improving blood pressure levels.

Mental and Emotional Health

The 2024 UCSF feasibility study demonstrated that the combination of infrared saunas and cognitive behavioral therapy led to decreased depressive symptoms in study participants. Multiple studies have established that cold baths provide significant benefits to mood and anxiety relief and concentration improvement which persist for several hours.

It is worth noting that alternating cold and hot can serve as an auxiliary tool to support emotional health, but it cannot replace clinical treatment.

Exercise Recovery

This is the most familiar application scenario among athletes. Comparative therapy can accelerate the removal of lactic acid and inflammatory active substances. A systematic review published in PLOS ONE in 2025 confirmed that cold baths have a clear alleviating effect on muscle soreness after exercise and can improve the next-day exercise readiness.

Sleep and Immune Function

• The rapid drop in body core temperature caused by saunas has a beneficial effect on falling asleep and improving sleep quality.
• Cold baths can stimulate the immune system. Experiments have shown that regular cold bath sessions can reduce the number of sick days by nearly 30% for the participants.
• The combination of the two may bring a more comprehensive immune regulatory effect, but more RCT studies are needed to confirm this aspect.

Not Omnipotent: Controversies, limitations and risks

The health market for contrast therapy is rife with excessive packaging and numerous inaccuracies. Some of the significant limitations and risks should be taken seriously.

Cold showers after strength training may slow down muscle growth.

This is the most important point for athletes to pay attention to. If your goal is to build large muscles or increase strength, regularly taking cold showers after strength training may inhibit muscle strength growth and endurance adaptation within 8-12 weeks. The reason is that cold water significantly reduces the inflammatory signals in the muscles after training, and these inflammatory signals are one of the key factors for training adaptation.

There is a significant lack of data on women.

A study conducted in 2025 using a randomized controlled design confirmed that cold and hot baths did not provide better muscle recovery for women after exercise compared to the control group (PMID: 40333546). A large number of studies have mainly used men as their samples, and the average cardiovascular response of women to cold and hot stimuli is generally greater. Applying the conclusions drawn from men to women is not appropriate.

The risks for special groups

People with heart disease or high blood pressure: Exposure to cold water too quickly can cause blood pressure to spike and increase the burden on the heart, with serious consequences.

Pregnant women: It is not recommended to immerse in any extreme temperatures.

People with low blood pressure or unstable blood vessels: Alternating between hot and cold causes drastic fluctuations in blood pressure, increasing the risk.

Those with skin conditions in the active stage or with larger injured areas: Avoid entering the water.

What should be done? The research-supported protocol

Basic protocol (suitable for most healthy adults)

1. Sauna for 15–20 minutes (temperature check, 80–90°C)

2. 5 minutes of learning - allowing the heart rate to stabilize slightly and reach equilibrium

3. Cold bath for 2–4 minutes (10–15°C) - this temperature range is most supported by research

4. Repeat 2–3 times, total duration 60–90 minutes

5. It is recommended to end with cold to optimize the sustained effect of increased dopamine and norepinephrine levels

Want to unwind and end the day?

If your goal is to relax and sleep better, ending with heat is a good choice - the heat from a sauna and steam can help you enter the rest mode. Ending with cold is suitable for activities during the day that require staying alert and focused.

Common Misconceptions Clarification

Misconception 1: The colder the water, the better.

The commonly used temperature is 10–15°C. The peak of norepinephrine occurs within 2–3 minutes after cold water immersion, and the benefits diminish after 5–8 minutes while the risk of hypothermia significantly increases.

Misconception 2: A single cold bath can burn 300–500 calories.

A 3–5 minute cold bath actually consumes approximately 15–25 calories, which is equivalent to 2–3 minutes. The help of cold baths for weight intervention mainly comes from the conversion of subcutaneous fat and the decrease in metabolic rate, rather than the single calorie consumption.

Misconception 3: It should be done every day.

For healthy adults, it is advisable to do it 3–4 times a week. Doing it too frequently will cause the autonomic nervous system to remain in a state of tension for a long time, and deprive it of its normal recovery function.