Stiff neck problem from sleep is quite a common problem that puts a person in immense trouble to move the head. Once you are suffering from it apply heat and cold on the neck. You can also try over the counter medicines. Try to stretch the neck gently or do self-massage as it relaxes and loosens stiff muscle and ligament and improves flexibility. Adjust your sleeping position and find the right pillow to help your neck stay away from stiff muscle problem.
**Disclaimer- Information presented here is not intended to be qualified medical advice. Nothing expressed herein creates a doctor-patient relationship.