The most common form of headache experienced by Americans today. Statistics show, as many as 95% of the U.S. population has at least one episode of tension headache in their lifetime. Tension headaches are usually caused from muscle tension in your neck, shoulders and upper back. This tension is sometimes the result of poor posture, and, less frequently some sort of trauma (like a car accident). 

Symptoms

• More than 90% of tension headaches occur on both sides of the head. 
• The pain is usually dull and can build gradually throughout the day. 
• Sleep often helps a tension headache but they are also known to continue into the night and even after waking up.