Tokugawa Ieyasu (1542-1616), the first shogun of the Tokugawa shogunate, was a "drug aficionado" who made his own medicinal preparations. It is said that he always kept a remedy for heat exhaustion on the rear of his samurai hat. Who knows how effective the medicine actually was, but it's clear Ieyasu practiced vigilance against the possibility of heatstroke during battle.

In the latter years of the Tokugawa shogunate, the 12th shogun Tokugawa Ieyoshi (1793-1853) is believed to have died from heatstroke. The month of July 1853 -- the same month the black ships under the command of U.S. Commodore Matthew Perry arrived off the shores of present-day Kanagawa Prefecture -- was a brutally hot one. The 60-year-old Ieyoshi collapsed and died around this time. In his book, "Tokugawa shogun-ke jugodai no karute" (Medical charts from 15 generations of the Tokugawa clan), writer and doctor Tatsuaki Shinoda speculates that Ieyoshi died from heart failure caused by heatstroke.

No tradition of retreating to cooler climes to escape the heat of summer had existed among Japanese emperors and shogun. Until the Meiji Era, when foreigners who found Japanese summers unbearably hot began to build summer retreats in the cooler Shinshu region and elsewhere, the Japanese, regardless of whether they were powerful, rich, or mere commoners, suffered equally through hot, humid summers. Under such conditions, shogun, who were without many choices in their clothing and living quarters, may particularly have been at a high risk of heatstroke.

For days on end, high-temperature warnings have been issued in cities around Japan as we kick off the month of August. In just one week, over 8,000 people were transported to hospitals for heatstroke. Sixteen people have died. Many news reports have been about cases among students at school sports team practice, but close to half of those taken to hospitals for heat exhaustion have been aged 65 or older.

According to some reports, computer analyses show that 65 year olds, compared to 25 year olds, do not start sweating until air temperatures are higher by 3 degrees Celsius, and their body temperatures can rise more sharply than that of their younger counterparts. Bathrooms, where heat can easily become trapped, kitchens, and bedrooms without good ventilation are especially dangerous, and we urge older people to use their air conditioners effectively.

Weather forecasts say we can expect extreme heat over a wide range of the country, between the Tohoku and Chugoku regions, especially at the beginning of this month. Let us follow Ieyasu's lead and take necessary precautions against the heat, making sure that we're getting enough fluids and salt. ("Yoroku," a front-page column in the Mainichi Shimbun)