You sleep, you wake, but your arm is numb. Then comes that tingly sensation known as “pins and needles.”
What is this all about?
It’s called paresthesia. Most of the time, paresthesia, or “sleepy arm,” occurs when pressure from sleeping on your arm, or sitting with your legs crossed for a long period, blocks blood flow to nerve fibers in some part of your body.
A symptom of something going on
“Paresthesia doesn’t really cause harm. It’s a symptom of something going on,” said Dr. Rodney Sorensen, a Marshfield Clinic neurologist. “It’s like pain that way. The pain is not the problem but an indicator that something’s wrong.”
“The strange thing about paresthesia is that it doesn’t typically happen when you’re using your arms, hands or legs. Instead, it occurs at night when you’re resting them.”
The best known form of sleepy arm is carpal tunnel syndrome, a wrist injury commonly caused by repetitive usage like typing or playing a keyboard. About 20 percent of people will have carpal tunnel syndrome at some point.
Sorensen compares paresthesia to a copper wire with some of its outer insulation removed. With paresthesia, the nerve covering known as myelin is somehow damaged.
“When that happens, the nerve does odd things like cause sleepy arm,” he said. “Some describe it as a short circuit.”
Sleepy arm is not usually serious
“Sleepy arm” is not usually serious but can become so if left untended so you should see your doctor if it happens routinely.
“It can get worse to the point that nerves stay numb all the time until the problem is addressed,” Sorensen said. That may mean surgery to relieve pressure on your nerves.
Some people get quite concerned about sleepy arm because it feels odd, “but it is quite a common thing,” Sorensen said. “It usually isn’t caused by a serious problem and I’ve been able to reassure a lot of people about that.”