Extreme metal may be occasionally relaxing for some, but it's more stimulating than it is relaxing I think it's safe to say. It's a powerful rush, it's thought-provoking and high serotonin/adrenaline. There are many things that fit that description, but don't necessarily come from a peaceful place. I think extreme metal, in its imagery and deep sensitivity, is an outburst of anguish, and an artistic expression of nihilistic chaos. If I listen to Blut Aus Nord, or Godflesh, or Cannibal Corpse, or doom death bands, to extend a wide bouquet of the extreme metal spectrum, that's what I feel on all fronts. The common denominator, the fuel, is that infatuation with aural violence and an expression of anguish.