What is the reason for arm ache?

There are two main reasons. The first is physical reasons, that is, when sleeping, the posture is wrong, which oppresses blood vessels, leads to poor blood circulation and makes the arm numb and uncomfortable. However, when the sleeping position is adjusted, the discomfort of numbness will fade. The second is pathological reasons, such as strain, scapulohumeral periarthritis, cervical spondylosis, rheumatism, hyperlipidemia, diabetes and so on. This situation will be characterized by frequent, long-term and slow recovery. If you sleep in a different position, you will still feel sore and numb, or it will get worse. This situation requires medical diagnosis.