Poor sleep habits may do far more damage than merely leaving you tired the next day. According to research by Dr. Fahed Hakim of Rambam Medical Center and an American team, poor-quality sleep marked by frequent awakenings can speed cancer growth.

This is the first time a scientific study has shown a connection between poor sleep habits and cancer, and its findings indicate that unsound sleep can cause tumors to become more aggressive, invasive, and intensive.

The study was conducted by Hakim and experts from the University of Chicago and the University of Louisville. It was carried out over two years at the University of Chicago, and led by Hakim, a pediatric pulmonary and sleep expert.

While many studies have shown a clear connection between poor sleep habits and fatigue or irritability, this research project indicates that fragmented sleep has far more dramatic effects. Not only do our muscles and mind suffer, but poor quality sleep leaves the body’s immune system sluggish, making it less able to fight and eradicate cancerous cells.

The research was based on observations of different sets of mice, with some mice allowed to sleep soundly, and others rudely awakened numerous times during the sleep cycle. The mice were injected with two different types of cancer cells, and all began developing malignant tumors. But after a month, the researchers found that tumors of mice with fragmented sleep were twice as large as those from mice that had slept normally.

A subsequent experiment revealed that the tumors the poor-sleep cohort contracted were not only larger but that they were also more malignant and aggressive, growing more quickly and larger than those the good-sleep mice contracted. The tumors of the sleep-disrupted group were not static, but invaded surrounding muscle and bone tissues.

“This study offers biological plausibility to the epidemiological associations between perturbed sleep and cancer outcomes,” said David Gozal, chairman of pediatrics at the University of Chicago Comer Children’s Hospital, who worked with Hakim on the study. “The take-home message is to take care of your sleep quality and quantity like you take care of your bank account,” he added.

The best response is simple, said Hakim – a good night’s sleep. And the best way to achieve that is to follow the tried and true wisdom dispensed by grandmothers and matronly aunts: Read a good book before going to sleep, unwind and relax, and maybe have a glass of hot, calming herbal (non-caffeine) tea. Whatever works.

“I do not want people to panic and think that waking up occasionally in the middle of the night will cause cancer,” Hakim said in an interview. “But the study is very clear. People need to sleep, ideally seven or eight hours a night.”