Menopausal hot flashes: their cycles and relation to air temperature

Area of Science:

• Physiology
• Thermoregulation
• Chronobiology

Background:

• Hot flashes are a common symptom, often associated with hormonal changes.
• The precise physiological mechanisms triggering hot flashes remain incompletely understood.
• Previous research has explored various potential triggers, including environmental factors.

Purpose of the Study:

• To investigate the temporal patterns and potential environmental correlations of hot flash occurrence.
• To explore the relationship between hot flashes and both internal and external temperature fluctuations.
• To propose a neurohumoral mechanism for hot flash generation influenced by external temperature.

Main Methods:

• Detailed daily recording of hot flash occurrences over 100 days by a single participant.
• Analysis of temporal patterns, including circadian rhythms and day-to-day variations.
• Correlation analysis between hot flash frequency and both outdoor ambient temperature and internal body temperature.

Main Results:

• Hot flash occurrence exhibited clear circadian fluctuations, with a peak incidence between 18:00 and 21:00 hours.
• The daily rate and timing of hot flashes were directly correlated with outdoor temperature.
• No significant relationship was found between hot flashes and internal body temperature, suggesting external thermal cues are primary drivers.
• The observed mechanism did not demonstrate acclimatization to heat.

Conclusions:

• External temperature, rather than internal body temperature, appears to be a significant modulator of hot flash frequency.
• A proposed mechanism involves external temperature receptors influencing a central neurohumoral pathway that activates the hypothalamic heat loss center.
• Further comprehensive studies involving larger cohorts of women are essential to validate these findings and elucidate the underlying physiology.