Feeling relaxed is usually correlated with a SUFFICIENCY of alpha waves, and conversely an anxious state of mind with an ABSENCE of alpha waves. 

•  A 2018 study found that those people experiencing an anxiety trait have BETA WAVES THAT OVERPOWER THEIR ALPHA WAVES, which over time accumulates into feelings of constant stress.
•  Other researchers  found that highly anxious people showed  MORE ALPHA WAVES IN THE RESTING STATE state (essentially are more relaxed) than less anxious people.  However, during a specifically designed so-called “Eriksen-Flanker Task” to make subjects alert and focused, both groups showed similar alpha wave activity. Seemingly counterintuitive, this observation seems to imply that alpha waves in a highly anxious person suppress the processing of external stimuli / information. Psychology and Physiological Science researchers  at Ball University