The dreaded charley horse: No one really knows how it got its name, but up to 60 percent of adults experience the occasional nocturnal leg cramp, which can feel like a painful spasm, tightening, or twinge.
Charley horses develop when the nerves that carry signals to your muscles fire off too many messages at once. This causes your muscles to contract in an uncomfortable way, says Scott Garrison, M.D., Ph.D., director of the department of family medicine at the University of Alberta.
Sitting or lying down for a long time—like when you’re sleeping—can trigger the nerve malfunction. That’s why you tend to get cramps in the middle of the night, and weirdly, charley horses are more common in warmer months, according to a new study from Dr. Garrison and his team.
It might be because you have higher levels of vitamin D in the summer, thanks to increased sun exposure. The nutrient plays a role in regulating the growth and repair of your muscle fibers, says Dr. Garrison. But more growth and repair may also send the muscle mechanism behind your cramps into overdrive, he says. Charley horses become more common—and painful—as you age, says Dr. Garrison. After you hit 50, you start losing more of the nerve cells that send messages from your brain to your muscles. The cells that are left have to work harder, which experts speculate might cause cramping.
Fortunately, the spasms are usually harmless. But in rare cases, they can signal electrolyte imbalance or neuromuscular disorders like amyotrophic lateral sclerosis (ALS), known as Lou Gehrig’s disease.
Stretching your calves, hamstrings, and quads before bed will stop cramps before they start. In fact, a 2012 study from the Netherlands found that older adults who suffered from charley horses experienced fewer, less severe spasms when they stretched their legs for 3 minutes prior to hitting the sack.
Your usual first line of defence—hopping out of bed and walking around for a minute—will help relieve tightness, too.