Waking up with numb, tingly hands, or a “pins and needles” sensation (paresthesia), is a common experience. This article explores the physiological reasons why it occurs when lying down and how to prevent it.
What Causes Hands to “Fall Asleep”
Hands “fall asleep” due to temporary pressure on nerves. Nerves transmit signals, and compression disrupts this pathway, causing tingling, numbness, or a “pins and needles” sensation (transient paresthesia). This brief interference with signal transmission causes the characteristic feelings. While blood flow supports nerve health, direct pressure is the immediate cause. Once pressure is relieved, the nerve typically regains normal function, and sensations subside.
Common Reasons When Lying Down
When lying down, certain postures can place pressure on nerves, causing hands to “fall asleep.” For instance, sleeping on your stomach with arms raised overhead can compress nerves in the shoulders or armpits. Sleeping on your side with an arm tucked underneath your body or pillow can also pressure nerves in the arm or wrist.
Pillow type and placement can contribute; a pillow that is too high or low might cause awkward neck angles, potentially compressing nerves leading to the hands. Tight clothing or restrictive jewelry worn during sleep can also constrict nerves, leading to temporary numbness or tingling. These positional factors usually cause temporary symptoms that resolve quickly once the position changes.
Deeper Medical Explanations
While temporary positional issues are common, persistent or recurring hand numbness when lying down can indicate underlying medical conditions affecting nerve function.
Carpal Tunnel Syndrome
This common condition involves compression of the median nerve at the wrist. It causes tingling, numbness, and pain in the thumb, index, middle, and part of the ring finger, often worsening at night.
Cubital Tunnel Syndrome
This condition involves compression of the ulnar nerve as it passes through the inside of the elbow. It can cause numbness, tingling, and pain in the ring and little fingers, often aggravated by prolonged elbow bending during sleep.
Thoracic Outlet Syndrome
This occurs when nerves or blood vessels in the space between the collarbone and first rib are compressed. It leads to pain, numbness, or tingling in the arm and hand, particularly with overhead activities.
Systemic conditions can also impact nerve function, leading to peripheral neuropathy, a type of nerve damage that often causes numbness, tingling, and weakness, commonly in the hands and feet. Diabetes is a frequent cause, as high blood sugar levels can damage nerves over time. Certain vitamin deficiencies, particularly B12, can impair nerve health and contribute to neuropathy. Hypothyroidism, an underactive thyroid gland, can also cause fluid retention that puts pressure on nerves, potentially leading to symptoms like carpal tunnel syndrome and peripheral neuropathy.
When to Consult a Doctor
Consult a healthcare professional if the sensation of hands falling asleep becomes persistent, worsens, or is accompanied by other concerning symptoms. Red flags include numbness or tingling that does not resolve after changing position, accompanying pain, or muscle weakness in the affected hand or arm.
Seeking medical advice is also important if symptoms affect both hands, interfere with daily activities, or are associated with other systemic symptoms. A doctor can determine the underlying cause through examination and recommend diagnostic tests or treatments. Early diagnosis and intervention can help manage the condition and prevent potential long-term complications.
Practical Tips for Prevention and Relief
To alleviate or prevent hands from falling asleep when lying down, several practical adjustments can be made. Modifying sleep positions is often effective; try to avoid sleeping directly on your arms or with your arms raised overhead. Sleeping on your back with arms at your sides can help maintain neutral alignment and reduce pressure on nerves.
Using supportive pillows that keep your neck and spine in proper alignment can also prevent nerve compression that originates in the neck or shoulders. Gentle stretching exercises for the hands, wrists, and arms before bed can improve circulation and reduce tension.
Additionally, ensuring that sleepwear or wristbands are not too tight can prevent constriction that might lead to numbness. For individuals who spend extended periods on computers, incorporating ergonomic practices during the day, such as maintaining a neutral wrist position and taking regular breaks, can support overall hand health and potentially reduce nighttime symptoms.