Who among us hasn’t woken up one morning with a giant, grotesque bruise taking shape on our arm or leg, yet with no memory of an injury that could have caused it? I know I’ve often asked friends and coworkers, “Ooh, how’d you get that shiner?” And more often than not, the response is a decidedly lackadaisical “Eh, who knows?” When you’re saddled with a sizable contusion, shouldn’t you at least remember the injury that caused it?
Bruises, the purplish swellings that happen when delicate capillaries meet blunt-force trauma, are an unpleasant fact of life (especially active, athletic, or clumsy lives). Bruises aren’t usually dangerous—the body eventually reabsorbs the blood that leaks into the surrounding tissues—but they can be disconcerting when they seem to show up without rhyme or reason.
According to the Mayo Clinic, random and unexplained bruising is common, especially among older people. Although we usually think of bruises as the result of painful bangs and bumps, they often show up after much less provocation than that. Any time the soft tissues in the body are injured, whether close to the surface of the skin or deep below, blood vessels can rupture and a bruise can form. For people who are prone to bruising, even a slight bump is enough to leave a mark.
The Usual Suspects
There are several simple reasons, and many not-so-simple ones, why some people are more bruiseable than others. For people who consider themselves bruise magnets, the most common cause is thin skin. Predictably, most bruises appear on the arms and legs, which usually have a thinner layer of protective fat than other areas of the body and therefore less padding to absorb the shock of an impact. Some medications can also alter skin’s thickness. Corticosteroids (like the topical creams prescribed for eczema and other dermatological conditions) can lead to thinning skin and increased bruising. The thin-skin theory also explains why women are more likely to bruise easily than men are (women have thinner skin), and why people bruise more frequently as they age (older people have thinner fat reserves under their skin).
