When you wake up with bruises, you should first consider whether there is a blood disorder. For example, some patients may have bruising when they have coagulation disorders or low platelet levels. This phenomenon is often caused when the skin of the body is crushed, bruised or stabbed. After bleeding from trauma, because the blood cannot be clotted quickly, the capillaries under the skin will keep bleeding, and the blood will gather under the skin to show the bruising phenomenon. When this phenomenon occurs, we should go to the hospital in time to test the coagulation function and platelet count to make a preliminary diagnosis. In addition, the bruises may also be caused by some allergic diseases. There is a disease called allergic purpura, which causes bruises all over the body. You can get a clear diagnosis through the relevant tests in the hospital and get timely and symptomatic treatment.