One Short Night Cuts Activity of Your Cancer-Fighting Cells by 70 Percent
The immune system's front line against tumors is exquisitely sensitive to a single bad night, and poor sleep helps cancers grow faster.
Talks at Google · Why We Sleep: Science of Sleep & Dreams | Matthew Walker | Talks at GoogleGet just four hours of sleep for one night, and the activity of your natural killer cells falls by 70 percent. That is the result described by Matthew Walker, a sleep scientist at the University of California, Berkeley.
Natural killer cells are immune cells that patrol the body for dangerous invaders. Walker calls them the Secret Service agents of the immune system, because they find early cancer cells and destroy them before those cells can become the disease we call cancer.
The drop matters beyond the lab. Short sleep has been linked to cancers of the bowel, prostate, and breast, and the World Health Organization has listed working overnight as a likely cause of cancer because it disrupts sleep rhythms.
In another experiment, David Gozal, a sleep researcher at the University of Chicago who studies sleep loss and cancer, gave mice cancer cells and restricted sleep in half of them for a month. Those tumors showed a 200 percent increase in the speed and size of growth, and the cancer spread to other tissues.
Walker said that fighting cancer without enough sleep may be the equivalent of "placing gasoline on an already aggressive fire."
Questions people ask
Does the body really make cancer cells every day?
Walker says your body produces cancer cells, and is always doing so. What stops those cells from becoming the disease we call cancer is, in part, these natural killer cells, which is why he says you want a strong set of these defenders at all times.
Does immune activity bounce back after you catch up on sleep?
The study found a 70 percent drop after one night limited to four hours, without giving a recovery timetable. Walker then asks listeners to imagine the state of the immune system after weeks, if not months, of insufficient sleep. The point he stresses is how quickly the harm appears.
How much sleep is enough to keep this defense working?
Walker points to National Sleep Foundation guidance and gives eight hours, with a range of seven to nine, for the average adult. He adds that your sense of doing fine on less sleep is a poor guide to how you are really doing, like a driver who insists he is fine to drive after drinking.