Bed bugs are primarily nocturnal creatures that like to come out at night. Their main source of food is your blood.  Bed bugs are attracted to human body heat and carbon dioxide you exhale while sleeping.  As soon as they detect carbon dioxide, they will come out of hiding for a nice blood meal. These pests will feed off of you, drawing blood anywhere from 3 to 10 minutes, or until they've had their fill and crawl back to their hiding place.When bed bugs bite, they feed on you by piercing the skin and withdrawing blood with their elongated beaks.  You will not feel the bed bug biting you because they inject an anesthetic, numbing chemical, and an anti-clotting agent so your blood flows freely. A bed bug will feed on you anywhere from three to ten minutes while you sleep and then quickly go back into hiding once they've had their fill.When you are initially bitten by bed bugs while you sleep, you will not feel it and it will not awaken you. Bed bug bites turn into red itchy welts on your skin, appearing on any areas where the skin is exposed while sleeping.If you've been bitten by bed bugs, depending on how you react to the bite, you may not show any signs of having been bitten. Bites may not appear the same day you've been bitten and may take a few days to show signs of bed bug bites. Bed bug bites commonly occur in clusters or zig-zag lines appearing as small red welts on areas where the skin has been exposed during sleep.The bites can be itchy and depending on the severity of how an individual reacts, the itching can become severe. Depending on the severity of the itch or if you already have some signs of infection, you may want to see your doctor.Over time, people become increasingly sensitive to bed bug bites, so the red welts and itching will grow in intensity the more often you are bitten. The symptoms of bed bug bites usually last around one to two weeks.  If you do find yourself with bed bug bites you will want to wash the bites with mild soap and water.  This will help reduce itchiness and help prevent infection. You can also use an over-the-counter anti-itch cream or ointment to help relieve the irritation and itch, as well as to help prevent infections as a result of scratching.