The sauna has been an integral part of many cultures for centuries – particularly renowned is the Finnish sauna, characterized by high temperatures and dry heat. But what actually happens in the body when we sit on the wooden bench at 80–100 °C? Is the sauna just relaxation, or is it truly a scientifically proven health tool?
This blog delves into the detailed physiological processes, health effects, and scientific findings surrounding regular sauna visits.
Heat as a Biological Stimulus: What Happens in the Body
Upon entering the sauna, the body immediately reacts to the intense heat stimulus:
- The skin temperature rises to about 40 °C within minutes.
- The core body temperature can increase by 0.5–1.5 °C.
- The heart rate increases significantly (similar to moderate physical activity).
- The blood vessels dilate (vasodilation).
- Heavy sweating occurs (up to 0.5–1 liter per session).
These reactions are not ‘stress in a negative sense,’ but a targeted stimulus that activates adaptation mechanisms in the body.
Impact on the Cardiovascular System
One of the best-studied effects concerns the cardiovascular system.
A large Finnish longitudinal study (Laukkanen et al., 2015, JAMA Internal Medicine) indicated:
Men who visited the sauna 4–7 times a week had a significantly reduced risk of:
- sudden cardiac death
- coronary heart disease
- fatal cardiovascular diseases
Why is the Sauna Heart-Protective?
1.Improvement of Vascular Function
The heat causes blood vessels to expand. This improves arterial elasticity and reduces blood pressure in the long term.
2.Blood Pressure Reduction
Regular sauna sessions can moderately lower systolic and diastolic blood pressure.
3.Training Effect for the Heart
The heart rate increases to 100–150 beats per minute during sauna use – comparable to brisk walking. This means the heart is stimulated without placing stress on joints or muscles.
The sauna does not replace endurance training – but it can complement it effectively.
Effects on Muscles and Recovery
For athletes, it is particularly interesting whether the sauna can improve recovery.
Studies show:
- Improved blood circulation in the muscles
- Faster removal of metabolic waste products
- Possible increase of growth hormones
- Muscle relaxation
The heat reduces muscle tension and may subjectively alleviate muscle soreness. However, the sauna does not replace active recovery (e.g., light jogging or mobility training).
Interesting is also the potential increase of heat shock proteins. These proteins support cell repair mechanisms and could contribute to adaptation to training stimuli.
Immune System and Susceptibility to Infections
Many people report that they get sick less often with regular sauna visits.
Scientifically, the following can be stated:
- Moderate activation of the immune system
- Increase in certain white blood cells
- Improvement of mucosal blood flow
The alternation between heat and cooling trains the vascular response and can improve the body’s adaptability.
Important:
The sauna should not be used during acute infections or fever.
Impact on Stress, Psychology, and Sleep
The sauna is highly relaxing – and this is not just subjective.
Physiological effects:
- Reduction of cortisol (stress hormone)
- Release of endorphins
- Activation of the parasympathetic nervous system
Studies also show connections between frequent sauna use and:
- lower depression rates
- better subjective well-being
- improved sleep
The intense body warming in the evening can also promote the natural decline in body temperature later – an important mechanism for falling asleep.
Metabolism and Calorie Consumption
It is often claimed that the sauna burns a lot of calories. This needs to be differentiated.
The energy expenditure increases through:
- increased heart rate
- thermoregulation
- sweating
However, the additional calorie consumption is more akin to moderate physical activity – not intense training.
Weight loss after the sauna is primarily fluid loss, not fat reduction.
Overview of the Key Effects
| Area | Short-Term Effect | Long-Term Effect (with Regular Use) |
|---|---|---|
| Cardiovascular | Increased heart rate, vasodilation | Lower blood pressure, improved vascular function |
| Muscles | Relaxation, better circulation | Possible support for recovery |
| Immune System | Activation of specific immune cells | Reduced susceptibility to infections (suggestive) |
| Psychology | Relaxation, endorphin release | Improved stress resistance |
| Sleep | Tiredness after cooling off | Improved sleep quality |
How Often Should One Go to the Sauna?
Studies suggest benefits with:
- 2–4 sauna sessions per week
- Duration: 10–20 minutes per session
- 2–3 sessions with cooling phases
Adequate fluid intake is important.
Who Should Be Cautious?
Not advised or only after medical consultation:
- People with unstable heart disease
- severe cardiac arrhythmias
- acute infections or fever
- uncontrolled high blood pressure
For healthy individuals, sauna use is generally safe.
Conclusion: Luxury or Underestimated Health Tool?
The scientific evidence clearly speaks in favor: regular sauna sessions can strengthen the cardiovascular system, improve vascular function, reduce stress, and possibly even positively impact life expectancy.
The sauna is no substitute for exercise, healthy eating, or sleep – but it can be a powerful add-on for holistic health.
Heat is not an enemy – when used correctly, it is a training stimulus for the body.
