Anatomy | Physiology | Body facts on Instagram: "The science behind a hickey 🩸🧠 A hickey isn’t just a mark of affection—it’s basic biology in action. When someone sucks or applies strong pressure to the skin, tiny blood vessels called capillaries rupture under the surface. Blood then leaks into the surrounding tissue, creating a bruise that appears red, purple, or dark brown. Over time, your body breaks down this trapped blood. That’s why a hickey changes color—from reddish to bluish-purple, t