The pins and needles sensation in your hands when you sleep is usually caused by nerve compression or reduced blood flow to the nerves in your hands, wrists, or arms. Certain sleeping positions, such as sleeping with your wrists curled inward, hands under your face, head on your forearm, or your torso pressing on your arms, can compress nerves or reduce circulation, leading to temporary numbness and tingling. This sensation is your body's way of signaling that the nerves are not getting enough blood or are being pinched. Common causes include:

• Poor sleep posture causing nerve compression (e.g., carpal tunnel syndrome affecting the median nerve in the wrist).
• Position-related reduced blood supply to the hands.
• Underlying medical conditions like carpal tunnel syndrome, peripheral neuropathy, or cervical nerve issues.

If the pins and needles sensation is frequent, persistent, or accompanied by pain or weakness, it may be a sign of a medical condition that requires evaluation and treatment. Adjusting your sleeping position, such as sleeping on your back or side with arms relaxed, often helps relieve symptoms. If symptoms continue, consult a healthcare provider for diagnosis and management.