"Sleepwalking" has been noted by many commentators for its notably more mellow tone compared to Bring Me the Horizon's previous singles. Spencer Kaufman of Loudwire, for example, noted that the song "showcases [the band's] more melodic side", praising the "beautiful bridge in the middle of the track". Similarly, the ticket merchant AXS claimed that the song "showcased that [Bring Me the Horizon] could write more poppy songs that still maintained the aggressive style they have been known for", while Mike Hohnen of Music Feeds explained that the track "[hones] in on a far more mellow, ambient vibe". Speaking in a track-by-track overview of Sempiternal with Metal Hammer, the vocalist Oliver Sykes described "Sleepwalking" as "one of the more commercial songs on the record" and "one of [the band's] best-written songs".
