Hot Water Therapy for the Treatment of Menopause-related Hot Flashes

Menopause is the time at which menstruation stops and perimenopause is the period before, characterized by a continuous reduction in estrogen and progesterone levels in the blood. Concurrently, the reductions in estrogen leads to a rise in another hormone, orexin. The reduction in circulating estrogen and progesterone and the increase in circulating orexin have been demonstrated to play a major role in menopause-related hot flashes and night sweats, known as vasomotor symptoms (VMS), as well as other symptoms such as mood disorders.

While hormonal replacement therapy remains the most effective defense against VMS, there has been a progressive decline in its prescription due to side effects such as uterine bleeding, increased risk of thromboembolism, as well as increased rates of gallbladder, breast, endometrial, and urinary cancers, highlighting the need for alternative non-hormonal treatments.

Exercise, and specifically the thermoregulatory benefits of exercise (i.e. increased sweating and skin blood flow, as well as reduced core temperature), improves vasomotor symptoms in women going through menopause. Heat acclimation/heat therapy improves thermoregulatory responses by more than twice as much as exercise alone, however, to date, no studies have investigated the effects of heat acclimation on menopause-related vasomotor symptomology.

Accordingly, the purpose of this study will be to examine whether hot water bathing improves vasomotor symptomology, with the guiding hypothesis that hot water bathing will reduce vasomotor symptomology.

Recruitment For this study, we will aim to recruit 100 women who have either undergone or who are undergoing menopause and who self-report experiencing vasomotor symptomology.

Study protocol An initial visit will be organized during which the potential participants will complete a health screening and consent to participate in the study. After which, the participants will undergo a two week-long baseline period during which they will track their vasomotor symptomology using a vasomotor symptomology journaling template, as well as complete a standardized menopause symptomology questionnaire. The participants will be randomized into two groups: a hot water bathing group and a sham group.

Following the baseline period, participants will report to the climate chamber located in the Hybl center to have their thermoregulatory responses assessed. This will consist of slowly walking on a motorized treadmill in 99.5°F (37.5°C) and 30% relative humidity conditions, for 30 min after which the humidity in the climate chamber will be progressively increased until an inflection in the participants' core temperature is detected. Before and/or during these trials, core temperature, heart rate, whole-body sweat losses, thermal comfort, local sweat rate, and skin blood flow will be measured, and a 6 ml (~1 tsp) blood sample will be taken, to assess heat loss adaptations.

Next, the participants will begin their 10-day, hot water bathing sessions. The participants in the treatment group will be asked to submerge themselves in a bathtub filled with 105°F (40.5°C) water, and to remain at this depth until their esophageal temperature reaches 101.5°F (38.6°C). Based on previous hot water therapy studies using this protocol, this should take approximately 25-35 min. After attaining the target core temperature, the participants will be given a stool to sit on in order for them to remain at waist depth in the water in order to maintain their core temperature at 101.5°F (38.6°C) for an additional 60 min. Participants in the sham group will be immersed up to the shoulder in a 97°F (36°C) tub for 30 min and then to waist-level for another 60 min in order to mimic the same hydrostatic pressures as were experienced by the participants in the heat therapy group, but without the heat exposure.

Finally, following the heat therapy sessions, the participants will be asked to take hot baths at home once every four days (as this is the frequency needed to stay heat acclimated) for one month, while continuing to track their vasomotor symptomology. At the completion of this follow up period, they will complete a study exit survey that has questions regarding their experience in the study.