Studies show bouts of insomnia may predispose individuals to depressive illness. The correlation between sleep disorders and mood disorders holds true across age and gender lines. Update Date: 02/06/2008Christos Ballas, M.D., Attending Psychiatrist, Hospital of the University of Pennsylvania, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.