1. Nerve Compression

This is the #1 reason.

Sleeping or sitting in a position that puts pressure on a nerve

Leaning on your elbows too long

Holding your phone with your arm bent for a long time
This can pinch nerves like the ulnar nerve, radial nerve, or median nerve, causing numbness or tingling.

2. Poor Blood Circulation

If blood flow to your arm is reduced, the nerves don’t get enough oxygen temporarily and start “tingling.”
This can happen from:

Tight clothing or jewelry

Resting your arm above your head

Holding one position too long

3. Pinched Nerve in the Neck

A pinched cervical nerve can make your:

Arm

Hand

Fingers
fall asleep out of nowhere.
Often comes with neck stiffness or pain.

4. Vitamin Deficiencies

Low levels of:

Vitamin B12

Vitamin B6

Vitamin D
can cause nerve irritation and tingling.

5. Carpal Tunnel Syndrome

If the median nerve is compressed at the wrist, your hand/arm may “go numb” randomly—especially at night.

6. Anxiety or Hyperventilation

Stress can cause temporary tingling or numbness due to changes in oxygen levels and muscle tension.

7. Medical conditions (less common)

Diabetes (nerve damage)

Thyroid problems

Autoimmune issues

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When to see a doctor

Seek medical attention if:

The numbness happens often

It lasts more than a few minutes

You feel weakness or dropping things

It’s only on one side with severe pain