New Delhi, Jan 28 (ANI): A new study has revealed that poor-quality sleep marked by frequent awakenings can speed cancer growth, increase tumor aggressiveness and dampen the immune system's ability to control or eradicate early cancers. "Fragmented sleep changes how the immune system deals with cancer in ways that make the disease more aggressive," study director David Gozal, MD, chairman of pediatrics at the University of Chicago Comer Children's Hospital, said.