Stress headaches, also called tension headaches, are very common with 30-80% of adults experiencing this type of headache. They most commonly produce pain diffusely over the head and the back of the neck. They are triggered by tight neck muscles that pull against the scalp (apply "tension," as in "tension headache). Tensing of muscles can be a reaction to stress, which is one reason this headache has been named "stress headache." Tension headaches are considered chronic when they occur at least twice a week for several months.