Scientists are suggesting that regular sauna use, a practice known as 'heat training,' could help people in the United Kingdom better adapt to increasingly frequent and intense heatwaves. This approach aims to improve the body's ability to cope with high temperatures by enhancing its natural cooling mechanisms.
Professor Jari Laukkanen, a cardiologist at the University of Eastern Finland, explained that repeated exposure to heat can induce acclimation, making the body more tolerant. "As the body gradually becomes better at coping with heat, you may tolerate it better," he stated.
The suggestion comes as the UK experiences one of its hottest summers on record, with temperatures surpassing 30°C on 31 days so far this year. The country has already endured four heatwaves, prompting the UK Health Security Agency to issue heat health warnings.
Traditional sauna bathing involves sitting in temperatures between 70°C and 100°C (160–210°F) for 10 to 15 minutes, often followed by rapid cooling. This process, according to research, can improve the body's thermoregulatory responses. Adaptations can include earlier and more effective sweating, increased skin blood flow, a greater plasma volume, and reduced strain on the cardiovascular system when exposed to heat later on. These physiological changes can collectively help individuals tolerate hot environments more efficiently.
Beyond physiological changes, research also indicates that sauna use may influence behavior in hot weather. After enduring the heat of a sauna, individuals may become more attuned to their body's signals of heat exhaustion and are more likely to remember to hydrate properly.
Professor Laukkanen emphasized that heat training is most effective as a gradual process over an extended period. Typically, it involves 40 to 60 minutes of heat exposure daily for four to six days, yielding benefits that last about a week. However, longer-term adaptations are possible with more sustained training. "The available evidence suggests that adaptation develops through repeated, moderate heat exposure rather than a single sauna session," he noted.
He advised that shorter sauna sessions, followed by cooling and rehydration, are likely the most sensible approach. However, the effectiveness of sauna use in managing heat once a heatwave has already begun is less clear. While Finns commonly use saunas year-round, Professor Laukkanen cautioned that beginners should proceed with care.
It is important to note that there is no specific medical guidance for using saunas during a heatwave. Heat adaptation does not equate to complete protection from heat. "Sauna should be viewed as one possible way of training the body's heat-regulation systems, rather than as a 'treatment' or therapy for heatwaves themselves," Professor Laukkanen said.
He stressed that sauna use should never replace established public health advice, which includes staying hydrated, avoiding prolonged exposure during the hottest parts of the day, seeking cooler environments when necessary, and paying particular attention to vulnerable individuals. Those with acute illnesses, fever, unstable cardiovascular conditions, severe dehydration, or who feel unwell should avoid saunas until they have recovered.
The UK has experienced several heatwaves this year, with temperatures reaching as high as 38°C. Many areas have seen grass turn brown due to the dry and hot conditions.
