At first glance, "Disillusionment of Ten O'Clock" may seem like an odd, somewhat difficult poem. The title itself provides little clear information about what's to come—and, in fact, raises several questions! Who is disillusioned (disappointed), and why? Is it ten o'clock in the morning or the evening? Why does the time matter here?
The poem's first two lines begin to answer those questions with the mention of "white-night" gowns, which imply that it's ten o'clock at night and people are getting ready for bed. Those nightgowns are a stand-in for the people wearing them; after all, nightgowns can't literally roam around a house!
The lines also imply, however, that the nightgowns themselves are haunting the houses, as if they had a will of their own. Those nightgowns are thus personified (or, perhaps, ghostified). By referring to the nightgowns rather than the people wearing them, the speaker reduces those people to their outward appearance. They are defined by their plain pajamas, which all look the same. The plain white nightgowns become a symbol of the conformity, routine, and lack of creativity that haunt human society, just as the nightgowns haunt these houses.
Lines 1 and 2 establish several patterns that the rest of the poem will follow. They are fairly short and written in free verse (meaning they have no regular meter or rhyme scheme). They make what seems to be a straightforward statement, though that statement is actually surprising and a bit strange! The enjambment after line 1 creates a moment of anticipation, for example, and many readers might expect the next line to reveal that the houses to be haunted by ghosts—only to read on and discover that it's "white night-gowns" possessing these homes.
The speaker's attitude toward those nightgowns is difficult to know with certainty. The lines are so short and direct that they could be read in an almost deadpan way. That same brevity, though, can also be read as a sign of intensity, drama, and emotion. To that end, take a look at the rhythm of these lines:
The houses are haunted
By white night-gowns.
Again, these are free verse lines, so they don't follow any regular meter. But they still have rhythm—notice how "houses" and "haunted" both have stresses on the first syllable. Combined with the alliteration on the /h/ sound, the stresses make the line seem more intense, and perhaps even sinister. This effect is heightened by the clustered stresses of "white" and "night," which also form an internal rhyme.
Though the idea of houses being haunted by white nightgowns could seem humorous or absurd, the sound and structure of the lines indicate that the speaker probably isn't making a joke. As the rest of the poem will make clear, it is these white nightgowns—and the lack of imagination they represent—that cause the speaker's "[d]isillusionment" in the first place.