I have been sleeping wrong. i woke up today with pain when i press on the left side of the back of my head. my left arm and feet were tingly as well. is it dangerous?

Nerve inflammation: Bent neck sleeping positions can strain the neck and the nerves leading from your spinal column. This strain can cause extremity numbness/tingling. It is not dangerous, only uncomfortable. Try to identify what caused you to sleep with your neck bent and resting on the left side of the back of your head. Use ice at the back of your neck and ibuprofen to reduce inflammation.