IS THERE ANY BETTER feeling than waking up refreshed and rested after a really good night's sleep? That sensation might be an indication of how good high-quality sleep is for you, not just for meeting the challenge of the day ahead, but for your longer-term health and wellness. A growing body of research into the connection between sleep and chronic diseases has noted that there could be an association between shut-eye and your chances of being diagnosed with an illness such as diabetes or cancer later on. It seems intuitive that there might be a connection between sleep and cancer risk. After all, cancer is an overgrowth of cells that should otherwise have been regulated or repaired before they got out of control. Much of the body's work to regulate this cellular growth occurs during sleep. "So many things are happening while we're asleep," says Amanda Phipps, an epidemiologist and researcher at Fred Hutchinson Cancer Researcher Center in Seattle. "It's a time when we most efficiently repair DNA damage. The body is also doing things like controlling the growth of cells, turning on certain genes and switching off others and promoting the immune system. Sleep is a time for repair and restoration of our bodies, but it's more than just that. It's also building up our immune systems so we can better protect ourselves during the day." If that period of time when the body is busy rebooting and fortifying its defenses is chronically shortened or disrupted, it stands to reason that could eventually have serious repercussions for cancer risk down the road. "From a biological perspective, there are a lot of good reasons for us to suspect that insufficient sleep, chronic sleep debt or short sleep duration could have an impact on the development of cancer," Phipps says. "We know in particular that when people don't get enough sleep, when they're chronically sleep-deprived, we see that can lead to chronic inflammation and insulin resistance." Chronic inflammation has been associated with several kinds of cancer, and insulin resistance is a precursor to diabetes that occurs when your cells don't respond appropriately to the insulin the pancreas makes to help your cells take up glucose from your blood. Inflammation and insulin resistance can both "set the stage for cancer by contributing to DNA damage," Phipps says. In addition, "inadequate sleep also results in suppressed levels of melatonin," a hormone that promotes sleep but also "can play a role in protecting against DNA damage and acts as a tumor suppressor. When we're not getting enough sleep, all these things can happen, which in theory could really set the stage for promoting the development of cancer," she says. A few studies over the years have supported the notion that lack of sleep and poor sleep quality could be connected to cancer risk, particularly for lung and colorectal cancers. A 2017 study in the journal Environmental Health Perspectives noted an increased risk of breast cancer among participants who had higher exposures to nighttime light. These findings support the notion that disrupted circadian rhythms are part of the equation. Circadian rhythm is the "24-hour cycle of night and day or sleep and wake," Phipps explains. "So many of our physiological functions hinge on that and they're synced to that cycle. When we're not getting enough sleep or we're getting disrupted sleep and waking up in the middle of the night because of light or noise pollution, a screaming toddler or needing to use the bathroom or sleep apnea, all that really has a bearing on our ability to sustain a healthy circadian rhythm. And when our circadian rhythms get disrupted, all the physiological functions that are tied to that rhythm can also get disrupted, including control of cell growth, repair of DNA damage and gene expression. It's not just about sleep duration, it's also about healthy sleep patterns and good quality sleep that's consistent in its timing." Source
