SLEEPWALKING by Julie Myerson (Doubleday: $20; 207 pp.) A lot of things happen to Susan all at once. Round about her eighth month of pregnancy, her father kills himself, her marriage becomes stunningly unimportant, she begins seeing a ghost (a young, pale boy), and a painter falls in love with her after their first meeting. One could say she is attracting a lot of energy from the universe. Technically, the father is not much missed, since he has sexually harassed and repeatedly raped his frightened daughter all through her childhood. The husband, Alistair, is a brick--a nice, British brick. Myerson captures the haunting of her character, Susan, very well; a face in a rearview mirror, a voice behind her, a flash in the corner of the eye. The affair with the painter seems true also; the pregnancy makes it very sexy. Alistair is not quite fleshed out but that is because Alistair is not quite flesh, even in the end. The ghost, you suspect throughout but are not told till the end, is Susan's "poor, poor father, who had no love," and through the birth of her own son she is able to forgive him.