THE RHYTHM OF LIFE: CHRONOTHERAPY AND CANCER CARE
BY ANDREA MONGLER
Wake, sleep, repeat. Day in, day out. It’s a pattern we’re so familiar with that most of us give it little, if any, thought. The sleep-wake cycle is simply one of life’s daily rhythms. In fact, it’s one of our circadian rhythms. Put simply, circadian rhythms are physical, mental and behavioral changes that our bodies experience over a 24-hour cycle. They affect our sleep, our body temperature, our appetite, our hormones and more. And it turns out these daily rhythms may play a key role in cancer treatment.
A coordinated concert of cells
Circadian rhythms are controlled by “clock genes” in our cells. While every cell has around 20,000 genes, just a handful of these are clock genes. Despite their small number, their impact is huge. Because of clock genes, for example, you may grow tired around the same time each night and wake up around the same time each day. This circadian rhythm is your body’s way of making sure you get the sleep you need. Of course, many of us wake by alarm clocks, which interrupt our circadian rhythms.
When clock genes are disrupted, they in turn disrupt daily rhythms like the sleep-wake cycle. Anyone who’s ever had jet lag has experienced this firsthand.
Clock genes get their name because they function as miniature clocks, each with the ability to keep time on its own. In addition, these mini-clocks are synchronized with each other thanks to a central clock, technically called the suprachiasmatic nucleus (SCN) but commonly referred to as the circadian clock.
WHEN WE’RE THINKING ABOUT THE BEST TIME TO TREAT PEOPLE,
WE NEED TO THINK ABOUT WHEN THEY NORMALLY GO TO SLEEP. CONSIDERING THE FACT THAT PEOPLE ARE DIFFERENT FROM EACH OTHER IN THEIR DAILY TIMING, THIS ENDS UP BEING SORT OF THE ULTIMATE PERSONALIZED MEDICINE.
Erik Herzog, PhD, a chronobiologist at Washington University, compares the SCN to the Atomic Clock in Boulder, Colorado. The Atomic Clock keeps extremely accurate time, and clocks nationwide—on our computers and smartphones, for example—are synchronized to match it. Similarly, the SCN sends out signals in the body to coordinate all of the mini-clocks in our genes. “The SCN is this tiny little population of cells in the brain that’s like a conductor for the clock genes throughout the body,” Herzog says. “The result is a coordinated concert of cells that sings together on a daily basis.”