LAUSR

K LE B E R C O R D E IR O / S H U TT E R S TO C K .C O M R esearchers have long known that a poor night of sleep can lead to long-term consequences; multiple studies have linked disruptions in our sleep cycles with an increased risk of tumor formation or a worsening of existing disease.1 In a society that has long undervalued the importance of sleep, researchers are now increasingly focusing on how individuals can improve their ability to recharge. Fiona Barwick, PhD, a clinical assistant professor of psychiatry and behavioral sciences and director of the Sleep and Circadian Health Program within the Stanford Heath Care Sleep Medicine Center in Stanford, California, says that our slumber depends on 3 main systems. Sleep drive is a biological drive that works much like hunger; it builds as we awaken and becomes active, and then it declines as we sleep. The second is a circadian system that regulates much of our behavior and physiology and is in turn regulated in large part by changes in the light-dark cycle. The third system is stress, which can disrupt sleep through a state of hyperarousal. Multiple studies suggest that circadian disruption is a probable cancer risk, especially among shift workers. Greater light exposure may inhibit the production of melatonin, which not only promotes sleep but also enhances the immune system and suppresses tumor formation. The links between cancer and sleep loss are less clear, Dr. Barwick says, although a reduction in sleep opportunities due to work, chronic pain, or other life events has been associated with adverse health consequences such as heart attacks, stroke, diabetes, and high blood pressure. Cancer-related pain and fatigue may reduce activity levels and thus lower sleep drive, whereas cancer can dramatically increase stress levels. “Stress disrupts sleep for all of us. When you combine it with a lower sleep drive, it’s going to be even more likely to keep you awake at night,” Dr. Barwick says. Some patients with cancer have higher rates of insomnia, which interferes with sleep ability rather than opportunity. “With the sleep loss, if you were in bed, you’d actually be asleep,” she says. “With insomnia, you’re in bed and you’re awake.” The underlying mechanisms are unclear but may be due to an increased level of arousal at night.