The reason you crush your hands when you sleep is because you can change your sleeping position through the night.
Sometimes you may accidentally roll over onto your hands or put your hands under your body without realizing it and crush your hands or pinch your nerves in your arms.
Sometimes positions in which you sleep can place your joints, spine and tissues under tension, compression or both.
Your nerves are especially sensitive and can lead to numbness in the arms and hands when you sleep on them and put compression on them.
The numbness should go away within a few hours.
Sleeping with bent wrists can lead to pain or numbness due to compression of nerves and tendons in the wrist and elbow.
Stretching before bed and using a body pillow may help prevent discomfort for those who sleep in this position.
The act of curling one's hands inward during sleep may provide a sense of security, akin to wrapping oneself in a protective cocoon before drifting into sleep.