27 cards where the name includes “sleep”

Activated Sleeper (Dominaria United Commander #24)
Ajani, Sleeper Agent (Dominaria United #192)
Awaken the Sleeper (Phyrexia: All Will Be One #119)
Benalish Sleeper (Dominaria United #8)
Breath of the Sleepless (Crimson Vow Commander #11)
Charmed Sleep (Bloomburrow #388)
Emissary of the Sleepless (Shadows over Innistrad #17)
Evolved Sleeper (Dominaria United #93)
Fear of Sleep Paralysis (Duskmourn: House of Horror Commander #12)
Kongming, "Sleeping Dragon" (Masters 25 #20)
Pillory of the Sleepless (Masters 25 #213)
Savior of the Sleeping (Wilds of Eldraine #28)
Send to Sleep (Magic Origins #71)
Shanid, Sleepers' Scourge (Dominaria United Commander #4)
Sigil of Sleep (Duel Decks: Venser vs. Koth #25)
Sleep (Core Set 2019 #74)
Sleep-Cursed Faerie (Wilds of Eldraine #66)
Sleeper Agent (Tenth Edition #178)
Sleeper Dart (Ikoria: Lair of Behemoths #240)
Sleeper's Guile (Urza's Legacy #67)
Sleeper's Robe (Invasion #273)
Sleeping Potion (Planeshift #34)
Sleep of the Dead (Theros Beyond Death #66)
Sleep Paralysis (Core Set 2020 #75)
Sleep with the Fishes (Streets of New Capenna #61)
Stifle (Secret Lair Drop #1787)
Xantcha, Sleeper Agent (Commander Masters #362)

Though this query has ended, its relics still slumber in New Argive.