What really happens when your feet and hands "fall asleep"

November 06, 2017

A closer look at an all-too-familiar sensation

  • The tingling sensation is known as paresthesia
  • Never sleep with your arms above your head
  • Chronic numbness can be serious

If you are a habitual leg-crosser or tend to fall asleep on your arms, then you’re probably all too familiar with the uncomfortable and sometimes annoying tingling sensation you get once your limbs have “fallen asleep.” But what does that really mean? Known medically as paresthesia, your limbs become numb when constant pressure is placed on a nerve, causing a prickling or burning sensation. Luckily, the tingling feeling goes away once the pressure is removed.

Why does paresthesia occur? 

The sustained pressure on a nerve blocks signals from the brain traveling to other parts of the body. The nerves then become hypersensitive, and that’s what causes the feeling of “pins and needles.” It might seem strange that the effectiveness of nerves can be impacted this easily, but if you look closely at your arms and legs, you’ll notice how close the blood vessels are to the skin. Because nerves are also that close to the surface, it’s no wonder that putting any pressure on them at all can easily compress and block them.

Types of paresthesia

The good thing about paresthesia is that most of the time it’s temporary. Some other types of transient numbness include:

Saturday night palsy

When you fall asleep against a firm object, such as a wall or sofa armrest, the object can end up compressing the radial nerve in your arm, causing it to go to “sleep.”

Honeymoon palsy

This term comes from someone else putting pressure on your arm, causing the “pins and needles” sensation. Generally speaking, it happens when someone falls asleep on your outstretched arm – affecting the nerves and muscle functions.

Ulnar nerve entrapment

The ulnar nerve runs from your neck to the tips of your fingers. If you like to fall asleep with your elbow bent, it can compress and trap the ulnar nerve causing numbness in your arm.

How to avoid the “pins and needles” effect

  • Don’t sleep on your arms at night – wrap a towel around your elbow to prevent you from bending it while you sleep
  • Avoid raising your arms above your head while sleeping; this could reduce blood circulation and cause numbness
  • Exercise regularly to promote healthy blood circulation
  • Try not to fall asleep against a wall, or with your arm dangling off the side of the bed or couch.

When it’s not temporary

Although the cause of tingling could be due to temporary pressure, there are some instances where repetitive feelings of numbness could be related to another medical issue.

Pinched nerve

If you have pain in your neck and lower back, it could be possible you have a pinched nerve. Pinched nerves are caused by injury, posture and even health conditions such as arthritis. Speak to a medical professional if you are experiencing prolonged instances of tingling and numbness in your arms and legs.

Carpal tunnel syndrome

Carpal tunnel could be the reason why your hands always fall asleep at night. If you’re putting too much pressure on the median nerve in your wrist, you could be at risk for developing carpal tunnel syndrome. It may help to modify how you perform daily activities to reduce the amount of pressure on your wrists.

Diabetes

For those with diabetes, you may notice a tingling sensation in your hands and feet. This is because people with diabetes may also have disorders that cause nerve damage.

Keep in mind, most often than not, the numbness you feel when your limbs “fall asleep” will go away. But if it doesn’t, reach out to a medical professional in your area today to get more insight into the cause.