Hello, A nosebleed can be caused as a simple reason as minor trauma, dry air, medications or upper respiratory tract infections to more serious diseases such as blood, immune system disorders or tumors. A nosebleed may be anterior (90% of cases) in which the bleeding happens to occur from frontal blood vessels or posterior (rare and serious) - blood comes from the back nose blood vessels. Majority of nosebleeds are benign and do not require further evaluation if it is not recurrent, mild, stops on its own in a short time (15 minutes). For the single, mild nosebleed episode you do not need laboratory evaluation. But you should get your blood pressure monitored by home blood pressure monitoring as well as get blood glucose level controlled. Uncontrolled blood pressure along with diabetes increases the risk of nosebleed. You were in lying position when the nosebleed happened, probably the blood flow toward the back of your throat and formed a clot. If you experience recurrent nosebleeds or nosebleed does not stop within twenty minutes, a large volume of blood is coming out, you feel dizzy or tired you should immediately seek medical help. When you experience a nosebleed try to stop it by pinching your nose above your nostrils for 10 to 15 minutes. You should sit or stand and lean forward (never lie down). You may place an ice-pack to your nose. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Malik