indulgence

noun

the behavior or attitude of people who allow themselves to do what they want or who allow other people to do what they want

(source-Merriam-Webster)

I meet this word in the reading called The virtue of idleness. This word is found in the sentence “The lie-in – by which I mean lying in bed awake – is not a selfish indulgence but something essential to the art of living.” By knowing the meaning of the word, I can image the situation the author is describing.