A new animal study, published in the journal Cancer Research, shows that disrupted sleep could accelerate cancer growth due to its negative effects on the immune system. Researchers from the University of Chicago and University of Louisville divided the mice into two groups. Group one slept undisturbed and the group two had their sleep disturbed every two minutes with a brush that swept through the cages. The sweeping forced the mice to wake up and go back to sleep.
The mice experienced their perspective settings for seven days before being injected with cells from one of two different kinds of tumors. Nine to 12 days after injection, the mice began to develop tumors. The researchers examined the tumors for four weeks.
The mice who had disturbed sleep developed tumors that were twice as big compared to the mice who slept peacefully.
Researchers found that the undisturbed mice had more immune system cells called M1-type tumor-associated macrophages (TAMs), which are known to promote the immune system and stop cancer cells. However, the sleep-disrupted mice had more immune cells called M2-TAMs, which are known to impede the immune system and promote tumors through blood vessel growth.
Study leader Dr. David Gozal, M.D., chairman of pediatrics at the University of Chicago Comer Children's Hospital, said in a statement, “This study offers biological plausibility to the epidemiological associations between perturbed sleep and cancer outcomes… The take home message is to take care of your sleep quality and quantity like you take care of your bank account.”