Whether or not Murakami intended to address existentialist themes in his short story “Sleep,” there's no doubt that it contains elements of existentialism all the same.

For one thing, the sleepless world inhabited by the female protagonist is akin to living in a world without death. Unable to sleep, she is confronted by the felt need to create and impose meaning on her life, which she does, among other ways, by dressing up as a boy.

Being able to sleep would allow this Japanese housewife to escape her daily existence with all its numerous challenges. But as she cannot do so, there is nothing for her but to face up to the inherent absurdity of life and take up an attitude of resolution towards it.

This she does by going out at night even though she runs the very real risk of being attacked. In true existentialist fashion, what matters for the woman is not so much what she does as that she's at least doing something that involves taking a firm, independent stand in a world where too many people are content to live lives characterized by the identities imposed upon us by others.

In breaking free of her role as a housewife and mother, however briefly, the protagonist of “Sleep” is discarding the bad faith or self-deception, which for existentialists like Sartre, was a hallmark of contemporary existence for so many.