Numbness in the arm that occurs after waking up in the morning first depends on how long it has lasted.
If the numbness disappears within a short period of time or after moving the arm, it is usually not due to a disease, but may be due to a poor sleeping posture, resulting in compression of the nerves in the upper limbs.
If the numbness persists for a longer period of time and is not relieved, then it is important to consider whether there is a disease factor.