Why do shoulder muscles tighten up while sleeping?
In response to the enquiry: “Why do my shoulder muscles tighten up at night while I sleep?”
There are several causes: (1) pillow; (2) sleeping posture; (3) draft.
A pillow that is too hard and too high forces the head forward. The neck muscles are forced to stretch and bend. In the morning, the shoulder muscles will feel tight.
The back is bent when sleeping in the fetal position. The posture also stretches the back muscles, and in the morning, the shoulder muscles feel tight.
If there is a draft blowing directly at the neck and upper back while sleeping, the shoulders may feel the cool draft and tighten up while asleep.