The artwork was inspired by actual events in his life. In 1852, the painter's mother succumbed to tuberculosis. His two younger brothers later followed, and Waterhouse felt devastated. It was this emotional distraught that inspired the creation of the painting. In the Sleep and his half-brother Death painting, two youthful brothers are blending in the shadowy background gradually. The foreground youth is visibly in the light. He represents Hypnos, the god of sleep. The other youth lying next to the first one is deep in the dark background. He represents Thanatos, the Greek god of death. The figure in the light has a clasp on some poppies, which are popularly known to symbolise sleep, peace and death. This is, without a doubt, the state of the people in this painting. They appear to be calm and deep in sleep.

John Waterhouse was a firm believer of Romanticism, an artistic movement in the 1800s characterised by an emphasis on nature, imagination and emotions. This piece of work has extensively relied on the romanticism technique and a bit of realism. Waterhouse has significantly expressed his grieving sentiments on the painting, perhaps in a bid to symbolise how peaceful and similar sleep and death are. He has portrayed the tragic deaths of his younger brother in a symbolism theme, with vivid colours and a striking contrast in the lighting.

Unlike his previous work, where he was fond of painting beautiful women, which showed he was a great supporter of Femme Fatale, the Sleep and his half-brother Death work is a pure allegory of his emotions at the time. Sleep and his Half-brother Death was Waterhouse's first artwork to make it to the Royal Academy exhibition in 1874. Years later, many other fascinating art pieces by the painter also made it to the Royal Academy exhibition. He became one of the greatest artists whose work was regularly displayed in famous exhibitions. It is, however, unclear where the paint is today or where it went after the display in Royal Academy. However, it is strongly believed that John Aird bought it after the exhibition.