Hot Spring Baths in the Evening Could Reduce Cases of Hypertension

New research investigated the therapeutic effects of "onsen". Researchers from Kyushu University's Beppu Hospital reported that onsen bathing, most specifically after 7pm, was linked to lower cases of hypertension in over-65s. Onsen is Japanese for hot springs. Kyushu University founded the 'Onsen Therapy Research Institute' in the historical city of Beppu to study the therapeutic benefits of onsen. It conducts research on the health benefits of onsen and continues to make a name for itself as a national hot spring treatment research center.

Onsen - A Part of Japanese Lifestyle

"In 2011, the institute partnered with the city and conducted a massive survey of Beppu residents over 65 about their health and onsen habits. This is something that can be done uniquely in Beppu because onsen is a part of everybody's daily lives, especially for the elderly. There are local onsen facilities everywhere, and onsens can even be connected to the home utilities" , explains Satoshi Yamasaki, a Lecturer of internal medicine at the Beppu Hospital and first author of the study.

The study collected information regarding medical history, onsen habits, and even the type of onsen frequented by over 11,000 people. Since then, researchers have been going through the data, analyzing the connection between health and onsen use (1^✔ ✔Trusted Source
Hot spring bathing is associated with a lower prevalence of hypertension among Japanese older adults: a cross-sectional study in Beppu

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Researchers wanted to find out if long-term onsen bathing had any preventative effects on hypertension. Past research has shown that traditional thermal therapy and hot spring bathing are effective against various diseases including hypertension.

In their data set, the team was able to pull out 4,001 individuals who currently have, or a history of, hypertension. Their first analysis found that having hypertension also increased the likelihood for the individual to have a history of other pathologies. These were the usual suspects of pathologies correlated with hypertension such as gout, arrhythmia, renal disease, and diabetes.

Effect of Onsen Bathing on Hypertension

Researchers found that individuals who bathed in onsen after 7pm were roughly 15% less likely to have hypertension.

The team hypothesizes two main reasons for these findings: lower stress and faster sleep onset. Previous research has shown that faster onset of sleep can improve sleep quality and improve hypertension control. Moreover, thermal therapies such as sauna bathing have been shown to alter levels of stress markers in the blood and lead to better mitigation of hypertension.

Researchers acknowledge some limitations in their study. Selection bias is expected whenever a questionnaire is used. They also could not account for the respondent's daily lifestyle that could affect hypertension, or if they are being treated for hypertension medically or with onsen. Nonetheless, they found that habitual nighttime onsen bathing was associated with a lower prevalence of hypertension. To understand these results further, clinical trials and further research is required.

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Reference:

1. Hot spring bathing is associated with a lower prevalence of hypertension among Japanese older adults: a cross-sectional study in Beppu - (https://www.nature.com/articles/s41598-022-24062-3)

Source-Medindia