The motif of one figure watching another figure sleeping recurs in Picasso's art throughout his career. Variations include scenes with two women, a man and a woman, and a mythical creature with a woman. The female figures were often inspired by the women in his life at the time. One explanation for the persistence of this theme is the fact that Picasso worked at night and had ample opportunity to observe his lovers sleeping.
Gallery label from Picasso: Variations and Themes, March 28–September 30, 2010.