European thinkers have long associated sleep with death because of the two states’ shared qualities. Both states detach the subject from the living, waking world, for instance. The necessity of both sleep and death—and particularly how they come to people of all classes—means that they often act as common denominators between all humans. Kings and commoners both need to sleep, and neither can escape death.

Blake’s poem draws on this European tradition in its depiction of night. The speaker presents sleep and death as parallel states, both able to create “joy without ceasing” (Line 14) through either dreams or an “immortal day” (Line 40). When night comes, the speaker says “[f]arewell” (Line 9) to the “green fields and happy grove” (Line 9), which suggests they will be separated from the material world for longer than a night’s sleep. The poem’s angels serve as intermediaries for both death and sleep, further emphasizing the connection between the two states. The angels provide joyful dreams and “pour sleep” (Line 23) on the heads of animals otherwise unable to rest. The angels also act as “heedful” (Line 30) guides to the afterlife, and “[r]eceive each mild spirit” (Line 31) as the sheep and lambs die.