I've been dealing with a super fast heartbeat whenever I lie down in bed for the last 56 days. It's weird because I don't feel any pain or like my chest is congested, but I do feel a lot of anxiety. I'm 24, my height is 5'9", and I weigh about 80kgs. Whenever I'm walking or sitting, my heartbeat seems normal; it's just when I'm laying down that it speeds up. Do you have any idea what could be going on? Is it something serious?

It sounds like you may be experiencing a condition called orthostatic intolerance, where your heart rate increases when you change positions, such as lying down. This can be due to various reasons such as dehydration, anemia, or autonomic nervous system dysfunction. However, it's important to rule out any underlying heart conditions. I recommend you consult a doctor for a thorough evaluation. In the meantime, you can try increasing your fluid intake and consuming electrolytes. If symptoms persist or worsen, please seek medical advice promptly.