Characteristics of the survey respondents.

Hot spring bathing practice helps to manage hypertension. However, the details of the relationship between hot spring bathing and hypertension remain unknown. Older people are thought to be less adept than younger people at using digital devices such as mobile applications. Whether mobile application questionnaires, which have been increasing in recent years, can be used by older people is unclear. To address the knowledge gap regarding the management of older patients with hypertension, we prospectively evaluated mobile application and paper questionnaires regarding night-time hot spring bathing in respondents who had a choice of which to use. Changes in blood pressure because of hot spring bathing were evaluated. To investigate the effects of night-time hot spring bathing on blood pressure in adults, 1116 volunteers at 14 institutions in Beppu completed the study, including 562 in the mobile application questionnaire group and 556 in the paper questionnaire group. A total of 474 of 477 (99.3%) respondents aged ≥65 years used paper questionnaires. There was a significantly lower drop in both systolic and diastolic blood pressure after using hot springs in respondents aged ≥65 years than in respondents aged <65 years (p<0.001). An age ≥65 years, hypertension with medication, arrhythmia, depression, and using a chloride hot spring were independently and significantly associated with a lower drop in both systolic and diastolic blood pressure after night-time hot spring bathing (p<0.001). Night-time hot spring bathing was significantly associated with reduced blood pressure in older adults (p<0.001). Extending this research by examining how psychosocial factors in respondents aged ≥65 years influence preferences for mobile and paper questionnaires may be beneficial, and further investigation is warranted.