Effect of pinpoint plantar long-wavelength infrared light irradiation on subcutaneous temperature and stress markers

Laser Ther. 2013;22(2):93-102. doi: 10.3136/islsm.22.93. Epub 2013 Mar 31.


Background and aims: The current investigation was aimed at the development of a novel non-invasive treatment system, "pinpoint plantar long-wavelength infrared light irradiation (PP-LILI)", which may be able to relieve mental stress and reduce stress-related hormones. Materials (Subjects) and methods: We compared the subcutaneous temperature, blood pressure, the degree of secretion of stress hormones before and after pinpoint irradiations (wavelength: 8-11 μm; output: 30mW). The study enrolled 15 subjects (Japanese healthy adults; 8 males, 7 females; average age 47.8 ± 14.6 years). Two parts of the planter region were irradiated for 15 min respectively. The stress markers such as ACTH, salivary amylase and cortisol were measured. As well, core body temperature and blood pressure were analyzed before and after the irradiation.

Results: A series of experiments revealed increased body temperature, decreased levels of blood pressure and stress markers described above after the irradiation.

Conclusions: These results clearly suggest that the PP-LILI system will be quite useful for relieving stress and improvement of homeostatic functions in the body.

Keywords: Pinpoint plantar long-wavelength light irradiation (PP-LILI); blood pressure; body temperature; relieving stress; stress hormones.