For the last 15 years, I've experienced severe palpitations, waves of intense heat (rarely with sweats), and dry mouth during the night. This generally lasts all night, with brief periods of rest. Although now on HRT, this began in my mid-30's, seemingly unrelated to hormone imbalances. I've had a basic cardio exam, cortisol levels checked, as well as T4 thyroid. I've been to 4 physicians, who tell me it's panic attack, which it's not. This never occurs during the day, but it's basically ruined my life in terms of sleep deprivation. ANY ideas at all???