The title shares its name with the Robert Frost poem Acquainted with the Night, which is quoted on the first page. The book's structure uses twelve chapters, equating to twelve hours of night, from 6 pm to 5 am. Two additional chapters, "First Night" and "Night's Last Stand", bookend the twelve chapters as an introduction and conclusion. This hour-by-hour structure was used to move the narrative along logically while jumping between diverse topics. The topics range from such disparate subjects as culture, superstitions, natural history, physiology, and psychology so that reviewers variously called the book "a compendium", "a browser's book" and full of "encyclopedic mini-essays". Autobiographical passages are also included. One reviewer noted the format uses personal observations that lead to discussions of broad subjects with "side trips into relevant supporting materials".
The reviewer for the Quill & Quire cited the book as an example of a subgenre which an article in The Atlantic Monthly dubbed "mundane studies" referring to the ubiquity of the subject, like Mark Kurlansky's Salt: A World History and Witold Rybczynski's One Good Turn: A Natural History of the Screwdriver and the Screw. Dewdney's writing in Acquainted with the Night combines a poet's point of view with an interest for the sciences. The tone was described as "boyish enthusiasm" and "highly condensed yet personable voice". Gisèle Baxter, in the journal Canadian Literature, wrote that the its tone was set at the beginning of the book by "an anecdote of a small boy creeping into the moonlit, partly wooded backyard of his family home".