Dear Doctors: My arms and hands have begun to go numb when I'm in lying down in bed at night. It wakes me up, so I'm not sleeping well. What causes this? I'm healthy, eat a pescatarian diet and exercise regularly. I don't have diabetes, but I may have high blood sugar. Should I see a doctor?
Dear Reader: When our ancient ancestors began to walk upright, they earned us some important evolutionary advantages. These include increased agility, improved endurance and freeing up our arms and hands to carry loads and manage tasks. The vertical stance led to increased flexibility of our spines and a remarkable range of motion in our joints. It increased our odds of survival, but it also came at a price.
Becoming bipeds left us more vulnerable to the effects of gravity and, thus, to a host of back and other skeletal problems. It's a risk that persists even in sleep. When the skeletal muscles relax, the pull of gravity takes over. This results in sustained, and often uneven, pressure on the joints and connective tissue of the shoulders, legs and hips. Depending on variables such as someone's age, weight, skeletal structure, general health and fitness and existing injuries, this can have an adverse effect on the nerves involved in motion and sensation.
One area that turns out to be particularly susceptible is the cervical spine. This is the series of seven vertebrae that support the head and neck. They also play host to a bundle of interconnected nerves known as the brachial plexus. These nerves branch into the upper torso and control motion and provide sensation to the arms, wrists, hands and fingers. If any of these nerves get compressed, damaged or lack for oxygen and nutrients, it can cause tingling, a pins-and-needles feeling or numbness. It can also result in muscle weakness.
Compression can arise from something as simple and reversible as poor physical positioning. A number of conditions can play a role, as well. This includes stenosis, which is a narrowing of the spinal column; arthritis; carpal tunnel syndrome; repetitive stress; degenerative diseases; infection; and physical injuries. Tingling and numbness can also arise due to damage to the nerves themselves, whether from illness or injury. This is known as neuropathy. Your mention of possibly having high blood sugar is also very important, as it is a risk factor for neuropathy.
Lifestyle changes can be effective. Begin by assessing your sleep habits and environment. Proper support from a mattress and pillow will ease potential pressure points in the head, neck and upper torso. Avoid lying with your arm under the pillow or stretched overhead, as this can compress nerves. A wrist brace can add stability during sleep.
With your combination of high blood sugar and persistent numbness, it's wise to discuss these symptoms with your doctor. Blood sugar management is crucial to good health, and your doctor can help you get yours under control. Your doctor may also suggest certain blood tests or scans that can help pinpoint the potential sources of this nighttime numbness.
(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
