Sleep formed in San Francisco in the early '90s. In '91, the band released their debut LP Volume One and earned comparisons to fellow Californians and Sabbath fans Saint Vitus. Sleep's Holy Mountain was a sonic breakthrough and is now seen as a foundational moment for stoner metal. The trailblazers signed to London Records, and in '95 they delivered their infamous third album, Dopesmoker, which consisted of one track over an hour long. London refused to release it, and Sleep decided to disband. They reunited in '09, making sporadic live appearances.