We identified night owl (nowl, Lztr1, CG3711), an ortholog of the human LZTR1 (leucine-zipper-like transcription regulator 1), as a modulator of night-time sleep in Drosophila. In humans, mutations in LZTR1 cause neurofibromatosis, a genetic disorder characterized by the growth of benign nervous-system tumors, that is most commonly known to result from mutations in Neurofibromin-1 (Nf1) [18, 19]. The gene discussed is NF1; the disease is hereditary disease.