Vasomotor symptoms (VMS) is the clinical name for hot flashes and their night-time form, night sweats. They are the most common symptom of the menopause transition, affecting up to about 80% of women.
They happen because falling estrogen narrows the range of body temperatures the brain tolerates, so it overreacts to small temperature rises by widening blood vessels and triggering sweating.
Vasomotor symptoms last a median of about 7 years and respond well to treatment, from lifestyle changes to hormone therapy and non-hormonal medicines.