The title plays a small trick: sleep is the "dream job," a pleasant phrase for ordinary rest, but also a kind of work. The speaker says it is "the work I spend hours in," which makes the night feel like a shift that has to be clocked in for. Nothing dramatic happens in it. The speaker simply lies down and lets the mind drift.
What drifts in is the speaker's father "and others." The poem doesn't say whether they are alive or dead, or what they did, so they feel like figures from memory passing through half-asleep thoughts. Then comes the poem's most striking phrase: "their legacy of evening." Instead of money or property, what the speaker inherits is a time of day, the winding down, the quiet and perhaps the tiredness of those who came before.
The mood is calm, reflective and a little wistful. The speaker seems to accept this inheritance rather than resist it.