By Mayo Clinic Staff. An X-ray is a quick, painless test that produces images of the structures inside your body â particularly your bones. X-ray beams pass through your body, and they are absorbed in different amounts depending on the density of the material they pass through.
Physical Causes. The most obvious reason for being tired and sleepy is lack of sleep. According to MayoClinic.com, the average adult needs between seven and eight hours of sleep every day. If you're sleeping less than that, adjusting your sleeping schedule might provide some relief.
Serotonin and Tryptophan. Serotonin and tryptophan may be the reason you feel sleepy after Thanksgiving turkey and mashed potatoes. Carbohydrates allow your brain to produce serotonin, a chemical that allows for calm and pleasant moods, while making tryptophan, the chemical responsible for sleepiness, more available to your brain.