<s>[INST] I have heart palipitations and an increased heart rate at night once I lay down to go to sleep.  They happen throughout the night and even wake me from sleep.  Do you any idea what could be causing this?  Heart desease does not run in my family and Ive never really had heart issues. [/INST] Hello! Welcome and thank you for asking on Chat Doctor! I understand your concern and would explain that your symptoms may be related to anxiety or autonomic dysfunction related to nightmares. Coming to this point, I would recommend performing a careful physical examination and some tests:-resting ECG and cardiac ultrasound-chest X-ray study-blood lab tests (complete blood count, thyroid hormone levels, blood electrolytes, kidney and liver function tests, etc.) to exclude other causes of increased heart rate. An ambulatory 24-48 hours ECG monitoring would be necessary to examine your heart rhythm trends during day and night and exclude possible cardiac arrhythmia. You should discuss on the above issues with your attending physician. Hope you will find this answer helpful! Best regards! </s>