When it comes to stoner-metal education, knowledge of Sleep is fundamental. Along with early-’90s acts like Kyuss and Electric Wizard, Sleep helped lay the groundwork for blasting heavy riffs into psychedelic meanderings, emphasizing the “stoner” part of stoner-metal more than most. Its seminal 1993 album, Holy Mountain, heaves with down-tuned dirges and Sabbath-derived rumblings. The long-awaited follow-up, 1998’s Jerusalem, is likewise an ambitious effort: It features a single hour-plus track, deemed by its label at the time as “unmarketable.” By the time the album/song was reissued in 2003 as Dopesmoker, Sleep had faded into legend, and its three members had splintered off into other crucial stoner-metal projects like High On Fire and Om. Fortunately, an invite to play All Tomorrow’s Parties in England in 2009 reunited the band for an ongoing tour.