Hello! Welcome and thank you for asking on HCM! Your symptoms seem to be related to nightmares and anxiety. You should know that some sleep disorders ( like nightmares), can be associated with an hyper reaction of autonomic nervous system leading to tachycardia, sweating, body shaking etc. I recommend consulting with your GP for a careful physical examination, a resting ECG, a chest x ray and some blood lab tests (thyroid hormone levels, fasting glucose, blood electrolytes, etc.). A polysomnography and an ambulatory 24-48 hour ECG monitoring are necessary to exclude a sleeping disorder or a cardiac arrhythmia. If all the above tests result normal, you should consult with an anxiety specialist, to help you manage your anxiety. Axiolytics and behavioral therapy would be helpful in your situation. Hope to have been helpful! Best regards, Dr. Iliri