Hi, i have read your query and if you had walked into my clinic with the following complains- - Palpitation which is worse on lying down. -Pins and needle in left arm, hand and leg. -feeling uncomfortable in chest. -Extreme work stress. -On Thyroid Medication I would think of the following possibilities three possibilities- 1- Heart disease- as heart has to work harder in lying down position to pump blood throughout the body. Hence, you may be experiencing palpitation on lying down. Similarly heart problem may cause chest discomfort and pin and needle sensation in left arm and hand. 2- Stress- certainly stress may can cause your heart to beat faster or the feeling that the heart is skipping beats and chest discomfort. 3- Thyroid Problem- I don t know what thyroid medication you are receiving but over-functional thyroid may present with palpitation, chest discomfort etc. Similarly if you are receiving thyroid hormone for under functioning thyroid, excess thyroid medication itself can cause symptoms like you have. I would suggest ECG, ECHO and Chest X-Ray to rule out any Heart problem, TSH to rule out thyroid problem and would suggest yoga and medication to reduce stress. Once test results are back i would go for specific treatment or further investigations. Hope this has helped you Regards