Disrupted Sleep Linked to Increased Cancer Risk From Weakened Immune System, Study Warns

Well, this is sure to make you sleep easier: Tossing and turning all night doesn't just make for an exhausted following day — it could also increase your risk for cancer. A new study shows that disrupted, poor-quality sleep can speed up tumor growth and diminish the immune system's ability to eliminate early cancers. When you wake up frequently, your body changes the way it handles the disease, making it more aggressive.

Researchers from the University of Chicago and the University of Louisville studied mice housed in small groups. Mice normally sleep during the day, so when the animals were busy catching their z's, a quiet, motorized brush moved through half of the cages every two minutes and forced those mice to wake up and go back to sleep. The rest of the mice were left alone to dream undisturbed.

After a week, both groups were injected with tumor cells (just when you thought it was bad enough they had to be woken up). Researchers analyzed the tumors four weeks later and found the mice who were disrupted in their sleep had tumors twice the size of those that slept normally. They also tested tumors injected into the mice's thigh muscle, which is supposed to contain growth. In the mice who were woken up, the growths were significantly more aggressive and invaded surrounding tissues.

"...In the fragmented-sleep mice, the tumors were much more invasive. They pushed through the capsule. They went into the muscle, into the bone. It was a mess," says study director David Gozal.

It's not the tumors themselves that are directly affected by sleep — it's the immune system. Well-rested mice had more immune system cells called M1-type tumor-associated macrophages (TAMs), which help stop cancer. The sleepy mice had more M2-TAM immune system cells, which promote tumor growth.

Sleep just does a body good in general. While you're dozing, your brain refreshes and is washed free of harmful toxins. Other studies have shown that sleep apnea increases a person's risk of dying from cancer. As Bustle reported:

"The take home message is to take care of your sleep quality and quantity like you take care of your bank account," Gozal says.

So get those seven to eight hours in. And maybe, don't have one of those babies.