Groggy, gravelly, grumpy. Most of us feel glum when we’re running on too little sleep, but not sleeping enough has implications beyond our general mood. For the 47 million of us in America who don’t get enough sleep (misery loves company), there are a number of health risks that we should keep in mind when deciding whether or not to burn the other end of the candle.
A ground-breaking new study published in the journal Cancer has found that people who sleep less than six hours per night on average had an almost 50 percent increase in the risk of colorectal adenomas compared with individuals who got at least seven hours a night. (Adenomas are a precursor to cancer tumors, and if left untreated, can turn malignant.) The study’s principal investigator, Li Li, MD, PhD, said that the increase in risk due to less hours of sleep is comparable to the risk associated with having a first-degree relative (parent or sibling) with colon cancer, as well as with high, red meat intake. Although why less sleep may lead to colon cancer is unknown, Dr. Li said some of theories include that less sleep may mean less production of melatonin, a natural hormone that in animals has been linked to DNA repair, or that insulin resistance may underlie the link between sleep disturbance and cancer development.
A connection between sleep and diabetes? Who knew? Women getting fewer than 5 hours of sleep each night are one-third more likely to develop diabetes, say Harvard researchers who conducted a far-ranging 10-year sleep study of more than 70,000 women (Diabetes Care, Feb 2003). The reasons that sleep problems might be connected to diabetes isn’t clear, but researchers think that too little sleep may reduce levels of leptin, a hormone that tells us to stop eating. Essentially, sleep loss may cause you to want eat more than your body needs. After going without enough sleep for two nights, people in one study had more of the hunger-inducing hormone ghrelin and less of the appetite-suppressing leptin.
Next: Heart disease
A University of Chicago study found that inadequate sleep caused levels of cortisol, the stress hormone, to rise in the afternoon and evening–increasing heart rate, blood pressure, and blood glucose. Along with abetting future health problems, the cortisol-induced alertness comes at a bad time–when you should be winding down your day or sleeping. In the same Harvard study mentioned above, researchers found that women who got less than 7 hours of sleep were at slightly higher risk of heart disease too. Sleep deprivation may hurt hearts by raising blood pressure, pumping extra stress hormones into the bloodstream, or raising blood sugar levels.
This one’s a no-brainer to any of who have had to be spunky and agreeable after too many nights staring at the ceiling. A 2002 National Sleep Foundation poll connects mood with sleep habits. Among those with sleep problems, 21 percent said they were dissatisfied with life, and 12 percent described themselves as angry. Nearly half had trouble getting along with relatives or friends, and more than 60 percent felt impatient waiting in lines or stuck in traffic. Dissatisfaction and anger were three times lower for those who said they get enough sleep. And they were more likely to describe themselves as “full of energy,” “relaxed,” and “happy.” says Joyce Walsleben, PhD, “sleep and mood are regulated by the same brain chemicals.”
Next: Traffic safety
Sleepless nights breed decreased reaction times–making driving (among other things) dangerous. A surprising National Sleep Foundation survey indicates that nearly 100 million sleepy Americans hop into vehicles each day. And each year, more than 100,000 motor vehicle crashes resulting in 1,550 deaths and 71,000 injuries are directly linked to drivers who fall asleep at the wheel. The US Congress is considering a bill that may put a stop to drowsy drivers. “Someone who gets behind the wheel drowsy, to me, carries the same risk as someone who gets behind the wheel drunk and should face the same criminal consequences,” says US Rep. Robert Andrews (D-NJ), sponsor of “Maggie’s Law” (HR968). The bill, which is named in memory of Maggie McDonnell, a college student who was killed by a sleep-deprived truck driver, would create traffic safety programs to be aimed at drowsy drivers.