The goal of this research is to assess the utility of smartphone-based progressive muscle relaxation (PMR) for the treatment of headaches. While there are many commercially available electronic diary and mind-body intervention apps for headache, there is little data showing their efficacy. RELAXaHEAD app incorporates the electronic PMR that was successfully used in an earlier epilepsy study and beta tested with headache specialist and migraine patient input. It also has functionality to track medications. This 2-arm randomized controlled study will evaluate the feasibility and acceptability of RELAX for use with headache patients. One arm will be the RELAX group (the RELAXaHEAD app) and the other arm will be a monitored usual care (MUC) group (this group receives standard of care and uses the electronic daily symptom reporting diary). The goals are to assess the feasibility and adherence of the RELAX intervention in persons with headache (Aim 1) and to gather data on the effects of the RELAX intervention on headache disability (Aim 2).