<s>[INST] age 58, female. after hiking 3 days in a row, when i lay down to sleep at night my heart feels like it is jumping around. i felt my pulse and i am skipping beats, which i think is normal for me. this has been going on since last tuesday night. it s friday now. when i sit up a bit in bed, the jumping stops enough so i can fall asleep. what s happening? [/INST] Thanks for your question on Chat Doctor. I can understand your concern. By your history and description, at your age (58 Yeats), arrhythmia (rhythm disturbances in heart) can cause similar symptoms. Arrhythmias like atrial fibrillation, atrial flutter, supra ventricular tachycardia etc. can also cause skipping beats. So better to get done ECG, 2d echo and Holder monitoring (24 hour continuous monitoring of ECG). You may need anti arrhythmia Chat Doctor.  Don't worry, you will be alright. Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks. </s>