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Stumbling upon circadian rhythms

PrintIn my job as a science writer, I get to hear lots of amazing stories of discovery. In some cases, researchers have worked diligently to solve one question for decades. Others I talk to describe exciting Eureka! moments where their data suddenly made sense. But some of my favorite stories are those where a scientist is studying one thing, only to make an off-the-cuff observation that leads them in a totally new direction.

In researching circadian rhythms for the latest issue of Stanford Medicine magazine, I heard lots of this last kind of story. There are many obvious ways that circadian rhythms influence biology: our sleep cycles, the way our stomachs start to grumble for lunch at the same time every day, and how many plants close their flowers each night. But scientists are also starting to reveal lots of hidden, unexpected ways that circadian rhythms - the natural cycles in living organisms - affect us. Over just the past few years, researchers in disparate fields have made chance observations that have made them think twice about the timing of their experiments; daily circadian cycles in our bodies can affect everything from how we metabolize drugs to how our immune system acts, they’ve found.

Craig Heller, PhD, who co-directs the Stanford Down Syndrome Research Center, told me about how he was testing a new drug to improve memory in mice with Down syndrome. During the course of his experiments, he noticed that mice who received the drug at night didn’t respond the same way as mice that received a dose in the morning. It led him to start investigating the link between learning, memory, and daily sleep cycles. What he discovered doesn’t just have implications for Down syndrome, but for learning and memory more broadly.

Then, sleep researcher Emmanuel Mignot, MD, PhD, of the Stanford Center for Narcolepsy, walked me through the story of how he and other scientists discovered a link between the immune system and narcolepsy. It all started, he explained, after an odd epidemiological observation: narcolepsy was more often diagnosed in the spring than in the fall.

Of course, lots of what we know about how circadian clocks tick along inside our bodies, keeping time with the world around us, comes from tireless, carefully planned out benchwork, and that can’t be discredited. But some of the most surprising new links I describe in my feature come from scientists taking leaps across fields to explain something they found curious. Check out my feature, “Hacking the Biological Clock,” to learn more about what Heller, Mignot, and other scientists have found on these journeys of discovery.

Sarah C.P. Williams is a freelance science writer based in Hawaii.

Previously: Stanford Medicine magazine reports on time’s intersection with health, Study shows altered circadian rhythms in the brains of depressed people and Narcolepsy = autoimmune disease
Illustration by Harry Campbell

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