During the second visit, the participants conducted a self-evaluation of pain intensity and quality of life after the next menstruation started (pre-treatment score) using the VAS and EQ-5D questionnaire. The third visit occurred at least 5-7 days from the date of the next menstruation, and a clinical primary nurse described how to use the medical equipment and devices when they were at home. All subjects were to perform the LLLT 20 min/day for 5 days from the start of menstruation. Within 3 days after menstruation started the subjects self-assessed their pain using the VAS after treatment (first post-treatment score). Subjects carried out the self-treatment in the same way at home 5-7 days before the start of their next period and then visited the hospital for the fifth time to record their pain on the VAS (second post-treatment score). As before, self-therapy was performed 5-7 days before the next menstruation started. The sixth visit occurred within 1-3 days after menstruation began, just as before, and all subjects performed the self-evaluation (third post-treatment score) using the EQ-5D questionnaire and VAS for menstrual pain intensity.