This study investigates the relationship between individuals' styles of day-dreaming and the occurrence of two types of sleep disturbance: insomnia and nightmares. Ninety-nine college undergraduates responded to a questionnaire consisting of subscales from the Singer-Antrobus Imaginal Processes Inventory and scales measuring extent of sleep disturbance; measures of response bias and samples of volitional waking fantasy were also obtained. Correlational and factor analytic treatment of the data indicated significant direct relationships between reports of sleep disturbance and the Guilty-Dysphoric and Anxious-Distractible daydream styles; sleep disturbance was unrelated to the Positive-Vivid daydream style. A response bias interpretation appeared insufficient to explain the findings. Aspects of the daydream styles also were found in the samples of volitional waking fantasy. Broader fantasy styles emerged which extend the daydream styles into the areas of volitional fantasy, sleep disturbance, dream recall, and mood.