Saunas are small, high-temperature rooms, typically heated to between 150°F and 195°F (65°C to 90°C). The combination of high heat and varying humidity levels often leads to the sensation of breathlessness or heavy breathing. This feeling is a direct result of the body’s physiological response as it works to regulate its core temperature. The perceived difficulty in breathing is not usually a sign of oxygen deprivation, but rather the body working harder to maintain a stable internal state in an extreme external environment.
The Body’s Immediate Response to Extreme Heat
The moment a person enters a sauna, the high temperature triggers a heat stress response. This automatic mechanism prevents the core body temperature from rising too high and requires significant internal effort to counteract the heat load.
The most noticeable physical reaction is a dramatic increase in cardiovascular activity. The heart rate can rise significantly, often reaching 100 to 150 beats per minute, which is comparable to the exertion of moderate-intensity exercise. This increase is necessary to boost cardiac output and circulate blood more efficiently throughout the body.
To facilitate cooling, blood vessels near the skin’s surface dilate, which shunts blood to the periphery. This higher demand on the circulatory system requires more oxygen to fuel the heart muscle and the body’s cooling mechanisms. The respiratory system responds to this increased metabolic demand by increasing the rate of breathing to take in more oxygen. This accelerated, yet often shallow, breathing is what is perceived as “hard breathing” or shortness of breath.
How Humidity Levels Affect the Airways
The moisture content of the air—or humidity—plays a role in the sensation of respiratory discomfort. Saunas can be broadly categorized as dry or wet, and each presents a different challenge to the airways. Traditional Finnish saunas, which are often dry with a relative humidity of 10 to 20 percent, can be particularly irritating.
In a dry sauna, the extremely low moisture content rapidly pulls water from the mucous membranes lining the nose, throat, and bronchial tubes. This drying effect irritates the respiratory tract, leading to a feeling that the air is sharp or causing a tickle that provokes coughing. This dryness makes the air feel harsher to inhale, contributing to the overall sense of breathlessness.
Conversely, a wet sauna or steam room operates at much higher humidity, sometimes approaching 100 percent. This high moisture makes the air feel heavy or dense because it is saturated with water vapor, making it harder for the lungs to achieve a full breath. The resulting labored sensation is often interpreted as suffocating. Furthermore, the high humidity significantly hinders the body’s ability to cool itself through sweat evaporation, which compounds the heat stress and the feeling of respiratory strain.
Managing Respiratory Discomfort and Ensuring Safety
To mitigate the feeling of labored breathing, several precautions can be taken before and during a sauna session. Adequate hydration, such as drinking water before entering, helps prevent dehydration-related drying and thickening of mucus in the airways. This ensures the respiratory tract remains moist and less prone to irritation from dry heat.
Regulating exposure time and position can also greatly reduce the strain on the body. It is advisable to limit sessions, especially for new users, to a brief 5 to 10 minutes, with a maximum of 20 minutes. Since heat rises, sitting on a lower bench provides a slightly cooler environment, which lessens the overall physiological demand and can make breathing feel less intense.
When breathing, focus on slow, deliberate inhalations and exhalations through the nose, which helps filter and pre-warm the air before it reaches the lungs. It is important to know the signs that the body is under too much stress, such as feeling dizzy, nauseous, or unable to catch your breath. If these signs occur, exit the sauna immediately and cool down gradually. Individuals with pre-existing respiratory issues like asthma or chronic obstructive pulmonary disease (COPD) should consult a healthcare provider, as the extreme conditions can exacerbate symptoms.