The Consumer Affairs Agency has issued a warning to elderly people to be careful when they soak in hot baths at home or at onsens, as well as spending too much time in saunas.
According to the agency, the number of victims who drowned after falling unconscious while taking a hot bath at home has increased by 70% or 4,866 people in the 10 years since 2004. Of that total, 90% were aged 65 and older, Fuji TV reported.
Most of the deaths, caused by heat shock, tend to occur from December to February, the agency said, with most fatalities reported in bathtubs.
The agency cautioned that when taking a hot bath, you can pass out due to blood pressure changes and also suffer from dizziness when standing up.
The agency advises elderly people to warm up the bathroom before taking a bath, set the water temperature to 41 degrees or lower and not soak in hot water more than 10 minutes.
As for saunas, the agency said steam in many saunas are electrically generated and temperatures can rise to as much as 52 degrees Celsius. Falling asleep inside a sauna can cause blood circulatory problems, health officials say.
Going into a sauna while drunk can also cause the body to become dehydrated. Many hotels post warnings outside saunas, urging people not to go in if they have consumed a lot of alcohol.