"The Sleepers" has always struck readers as a strange and haunting poem, and it caused a great deal of controversy right from the start. For many readers, the poem was simply a mystery. Whitman's friend and admirer John Burroughs wrote in 1896 that "There are passages or whole poems in the 'Leaves' which I do not yet understand ('Sleep-Chasings' is one of them), though the language is as clear as daylight; they are simply too subtle or elusive for me." Others, however, saw the poem's greatness immediately. Richard Maurice Bucke, another friend and disciple of Whitman, in 1883 pronounced "The Sleepers" as "among the very great poems," describing it as "a representation of the mind during sleep--of connected, half-connected, and disconnected thoughts and feelings as they occur in dreams, some commonplace, some weird, some voluptuous, and all given with the true and strange emotional accompaniments that belong to them." Dr. Bucke, who was a pioneer in psychiatry, found "the most astonishing parts of the poem" those passages where "the vague emotions, without thought, that occasionally arise in sleep, are given as they actually occur, apart from any idea--the words having in the intellectual sense no meaning, but arousing, as music does, the state of feeling intended." Bucke warned readers that the poem "requires a great deal of study to make anything of it," though to some few readers, he believed, "it would, no doubt, be plain at once."

Bucke's early psychological reading of the poem set the stage for growing interest in "The Sleepers" during the twentieth century. Critics often saw the poem as a proleptic examination of a model of the mind developed by Sigmund Freud and Karl Jung, who developed psychological theories that included submerged psychic levels inaccessible to the conscious mind: the "id" or "libido" or "collective unconscious" worked in invisible but powerful ways to organize our psychology. It was as if Whitman anticipated modernist literary and artistic movements that were built on the new psychological models. James E. Miller, Jr., read the poem as a "psychological dramatization of a flow of images with only eccentric relationships one to another, closely resembling the stream-of-consciousness technique of a later era" (p. 130). And Harold Blodgett and Sculley Bradley in the 1960s argued that the poem "is perhaps the only surrealist American poem of the nineteenth century, remarkable in its anticipation of later experiment" (p. 424).

"The Sleepers" became a favorite of psychological critics like Edwin Haviland Miller and Stephen Black. When Miller offered a long reading of the poem in 1968 as "an evocation of psychic depths" and "a reenactment of ancient puberty rites," he noted that "until recently" the poem "has been neglected and misunderstood" (pp. 72, 78). But seven years later, in offering his own psychoanalytical reading of "The Sleepers" as a revelation of "threats" that inhibited Whitman from "achieving a secure sense of identity," Black described the poem as "one of Whitman's most widely admired and analyzed poems" (p. 125). It was clearly a poem that had to wait over a century for the psychological approaches that would open Whitman's words in revealing ways. As readings of the poem proliferated, Jerome Loving would call it "the most famous dream in American literature" and post-structural psychological readings based on the ideas of theorists like Julia Kristeva developed the complexities of the poem.