What Makes Our Circadian Clocks Tick

It’s not just your imagination — as winter approaches, and the days grow shorter, our bodies are undergoing their own changes. The reason? Shifting circadian rhythms thanks to decreased exposure to light.

Circadian rhythms affect — and are affected by — a lot more than you might think.They determine our sleep-wake cycle, our hormones, our body temperatures, our moods, when we get hungry, digestion, immune function and more. And they’re affected by how we spend our days — when we eat, when we sleep, and how much time we spend under the glow of artificial lights.

On this episode, we explore the latest research on circadian clocks, and what makes them tick. We’ll hear about one woman’s experiment of sequestering herself in a dimly lit underground bunker for 10 days, and what it did to her internal clock. We’ll explore whether night owls can turn themselves into morning larks. And we’ll find out about new research on how the timing of taking medications can change their effectiveness.

Also heard on this week’s episode:

• We talk with science writer Lynne Peeples about an unusual experiment she tried on herself — descending into an underground bunker for 10 days, with no light and no clocks, to see how it would affect her circadian rhythms. That and more is included in Peeples’ book, “The Inner Clock: Living In Sync With Our Circadian Rhythms.”
• We visit the light research lab at Thomas Jefferson University in Philadelphia, where neuroscientist George Brainard studies how different kinds of light affect astronauts and their sleep patterns as part of an effort to develop an optimal new lighting system for the international space station.