The second daughter of Amanda and Andrew Tanning, Dorothea was born on August 25, 1910 in rural Galesburg, Illinois. Practically born with a pen in hand, she knew that she wanted to be an artist very early on. At age eighteen, Dorothea matriculated at Knox College, a small liberal-arts school in Galesburg; however, she only stayed for two years before moving to Chicago. In Chicago, she enrolled in the Chicago Academy of Art, where she found instruction too rigid and opted to gaze at the paintings at the Art Institute rather than attend her classes. Her true artistic awakening came in 1936 when she moved to New York and attended the famous exhibition Fantastic Art, Dada, and Surrealism at the Museum of Modern Art and discovered these avant-garde art movements.
In 1941, after working in the commercial art world for a few years, primarily for Macy's, Tanning was introduced to Julien Levy, New York's paramount dealer of Surrealist artwork. Whether it was because of her artistic style, her American upbringing, or her energetic beauty, Tanning gained ascendecy in the art world more rapidly than many of her female contemporaries. Levy signed Tanning on as one of his artists, and three years later, in 1944, Tanning had her first one-woman show at his gallery. While preparing for this show, Tanning became involved with Surrealist painter Max Ernst and she spent the summer of 1943 with him in Sedona, Arizona. They so enjoyed Sedona that they decided to get married and move there in 1946.
Three years later, Tanning and Ernst moved to Paris, and in 1954, Tanning had her first solo exhibition there at the Galerie Furstenburg. The following year, she had a retrospective in London at the Arthur Jeffress Gallery. To have shown in the three epicenters of the contemporary art world by age forty-five was quite an accomplishment for a female artist. The majority of the works that Dorothea had created up until then were marked by precision and accuracy, strong lines and meticulous shading. Even if the scenes depicted were unrealistic and teeming with fantastic elements, they were figurative and recognizable, painted with a strict attention to detail and linear composition.
In 1955, Tanning began to abandon this somewhat controlled, representational style in favor of a freer technique marked by raw energy, vibrant hues, and luminosity. This new period in her work was originally called her "prismatic" period, perhaps because these images appear distorted and fractured, as if looking at them through a glass prism. A few years later, Tanning herself began to refer to these works as "Insomnias," a name taken from a painting she created in 1957 while living in Sedona. She explains:
Beginning, roughly, in 1955, after a period of painting direct, simple images...my painted compositions began to shift and merge in an ever intensifying complexity of planes. Color was now a first prerogative: a white canvas tacked to the wall in Sedona would be blue and violet and a certain dried-rust red. It would have to be vertical. It would also be not quite there, immediately. I wanted to lead the eye into spaces that hid, revealed, transformed all at once and where there would be some never-before-seen image, as if it had appeared with no help from me. I was very excited and I called it Insomnias.