In the hot-spring heaven that is Japan, there are a countless number of onsen from Hokkaido to Okinawa, from those of luxurious spas in nondescript concrete buildings to rotenburo set in pristine natural surroundings.
Obviously what lures millions of onsen bathers back again and again is that wonderful feeling of just being able to close your eyes and forget about life's daily hassles – the boss, the crowds, the headaches. The relaxation effect of onsen, however, is just the tip of the iceberg.
"Onsen therapy has various medical effects," says Yuko Agishi, a 71-year-old physician and honorary professor at Hokkaido University. "It is a type of alternative or complementary medicine, not directly curing the cause of the disease but treating the body as a whole; assisting in recuperation, rehabilitation and disease prevention."
These medical benefits have given onsen a central role in balneotherapy, which is a comprehensive bathing treatment conducted to maintain health, normalize dysfunctions and prevent illness. Generally, the elements in this therapy are onsen, gases and climatic and geographical factors.
In the Edo Period (1603-1867), onsen therapy, then called toji, was widely practiced by the common people. For work-wearied farmers, toji was an especially valued feature of their hard lives. After a long day's work, they would go to an onsen to relieve their mental and physical strains as well as to ready their bodies for the next day's toil.
Just as those sons (and daughters) of the soil used toji to recuperate, so today's stressed-out workers are turning to "onsen therapy" (nowadays, generally termed "balneotherapy") as well.
Balneotherapy is often conducted in combination with other treatments such as aquatic therapy and massages.
"According to Archimedes' principle, a person experiences just one-ninth of their weight when underwater," says Agishi. "Therefore, it is a lot easier to move around and do exercises in the water. Aquatic therapy is most effective for those who need rehabilitation, whether because of a car accident or neurological disorders."
The onsen's chemical makeup is one of the key elements of balneotherapy. According to the 1979 revision of the 1948 Onsen Law, nine types of onsen water are recognized as having proven medical benefits. These are nisankatanso-sen (spring water high in carbon dioxide), tansansuisoen-sen (hydrogen carbonate), enkabutsu-sen (chloride), ryusan-sen (sulfate), tetsu-sen (iron), io-sen (sulfur), sansei-sen (acidic), hoshano-sen (radioactive) and tanjun (spring water that lacks these attributes but has a temperature of over 24 degrees).
"For example, sulfur onsen are quite effective for chronic articular rheumatism," says Agishi.
Bathing in these various types of onsen is used to treat other illnesses, such as arthralgia, chronic skin diseases, diabetes, constipation, menstrual disorders and so on. And by partaking of this natural therapy instead of using conventional medication, it is believed that people can also strengthen their immune system and thus enhance their ability to heal themselves.
There is, however, another way to absorb these minerals – insen (drinking medicinal spring water).
Of course, people don't drink the water they bathe in. Spring water specifically suited for insen is certified by the prefecture to be drunk unfiltered.
"Drinking onsen water has a stronger effect on the body than just bathing in it," says Agishi, "because the stomach and intestines directly absorb the water."
In Japan, however, the concentration of chemicals in spring water tends to be relatively low, so balneotherapy is focused mainly on bathing. By contrast, in many European countries spring water sources are rich in chemicals, and so people there tend to favor insen over onsen.
Among European countries, Germany has one of the most established systems for balneotherapy, and there are many facilities dedicated to onsen therapy. Typically, patients will stay there for three to four weeks, with the cost of their treatments often covered by insurance.
Similarly in Japan, onsen therapy may also be covered by insurance if a doctor's prescription states that a patient is in need of the treatment for a certain illness. But in practice, this constitutes a tiny proportion of the total, because onsen stays are generally regarded as a fun trip to be combined with eating good food, rather than as a part of medical therapy.
"In Japan, people generally visit onsen for one night only as a break from their daily routines," says Agishi. "And that is certainly refreshing. But from a medical viewpoint, onsen therapy takes at least three weeks."
Unlike in Europe, though, at present there are very few facilities in Japan offering such long-term therapy.
However, in 1996 the government-approved Minkan Katsuryoku Kaihatsu Kiko, known as Minkatsu (Organization for Development of Private Participation in Public Projects), was asked for assistance to promote onsen resorts at a time when many were going bankrupt.
Instead of concentrating on tourism, the association, to which Agishi belongs, focused on the medical aspects of onsen, and from 2000, Minkatsu officially started to take action.
One of their first accomplishments was the publication of "Onsen Ryoho no Techo (The Book of Onsen Therapy)" in 2002. This contains detailed explanations of onsen therapy and its effects, as well as a list of 310 doctors and specialists in the field so that readers can contact them for advice. The book also lists 509 onsen resorts with onsen therapy facilities, and their prices.
By disseminating information about balneotherapy to the public, Minkatsu also aims to encourage both local governments and private companies to build facilities for long-term onsen therapy.
"With the aging society, onsen therapy is what we need now," says Agishi. "It builds the confidence of old people because they can move around more freely in the water. This therapy will treat them without strain – and they'll enjoy it."
It is thought that the imminent graying of Japan is just what the ailing onsen industry needs.
According to Health, Labor and Welfare Ministry data, there are at present 23 million Japanese aged 65 and over. Toshiyuki Sato, the 73-year-old chairman of Minkatsu, estimates that when members of the dankai no sedai (baby-boom generation), who are now in their mid-50s, hits 65, there will be more than 30 million elderly people in Japan.
"In the near future, the elderly are going to be the key to Japan's vitality," says Sato. "With onsen therapy, the government can keep health insurance from rising, and the elderly can keep their health in order to work."
By Masami Ito (The Japan Times)