27 yo female-heart palpitations all night every night 3 months (sometimes no sleep). all labs have come back normal (no results on thyroid yet), two normal ekgs, nothing detected via stethoscope. no caffeine no anxiety prior to palps. possible cause?

If symptoms are recurring nightly, a cardiac monitor could be used to monitor your heart rhythm continuously for a week or more, enabling you to keep a diary and record your rhythm during symptomatic episodes. See a cardiologist for an appropriate evaluation.

While awaiting thyroid studies for possible hyperthyroidism/ Thyrotoxicosis, One should also consider Situational Stressors, in the Sleeping Environment as possibility. A Psychologist/Psychiatric consult might be helpful.