I will start by saying Sleep by Haruki Murakami is a favorite of mine. I read it in The Elephant Vanishes and later found a singular Portuguese version published by Alfaguara, and beautifully illustrated by Kat Menschik.
Sleep is the story of a Japanese housewife with prolonged loss of sleep—or something like insomnia—and her newly sleep-deprived world, in which she stood out from her ordinary everydayness. Her loss of sleep started when she saw a black shadow standing close to her feet at night:
He stood at my feet, perfectly still. He said nothing, but his piercing eyes stared at me. They were huge eyes, and I could see the red network of veins in them. The old man’s face wore no expression at all. It told me nothing. It was like an opening in the darkness.
How she felt after being more than a day awake? More alive and aware of herself, of her reality; she started to read again, go out at night, drink and eat chocolate (she was forbidden to by her husband).
The end is enigmatic and for the reader to draw their own conclusion (as expected if you have read Haruki Murakami before). Did she finally sleep? Was it a lucid dream? Sleep is short and easy to read. It might surprise you. I will revisit it when I can.