18: The Power of Your Internal Clocks: How Circadian Rhythms Shape Our Health with Lynne Peeples
EP. 18
For many women in midlife, sleep struggles, low energy, and weight changes can feel like an inevitable part of menopause. But an often overlooked culprit is circadian disruption. Hormonal shifts and the pace of modern life can throw off our internal clocks—the rhythms that regulate nearly every system in the body, from metabolism to mood.
When these clocks fall out of sync, it doesn’t just affect sleep. It can also disrupt hormone balance, increase the risk of chronic disease, and leave you feeling out of sorts without a clear reason why. And most of us have no idea how much these hidden clocks influence our daily lives—or how to get them back on track.
I recently spoke with science journalist Lynne Peeples, author of The Inner Clock: Living in Sync with Our Circadian Rhythms, who shared how menopause impacts circadian function and the powerful strategies she uses to restore rhythm and improve overall health—starting with small, daily shifts.
Listen to the full episode:
Circadian Lessons from the Seattle Mariners’ Locker Room
Lynne Peeples was touring the Seattle Mariners’ baseball stadium and locker room when something unexpected caught her attention. Before each game, the lights were bright, blue, and energizing—carefully designed to wake players up and get them game-ready. Afterward, the lights were dimmed and warmed to help the team wind down. The goal? To support players’ circadian rhythms.
That moment planted a seed—one that would eventually grow into a deep investigation into circadian health and her book The Inner Clock.
As she returned to life in Seattle, Lynne began noticing her own energy dips and sluggishness more acutely. She began speaking with circadian scientists and uncovering just how much our internal clocks influence everything from sleep and metabolism to mood, hormone balance, and even disease risk. The locker room lighting was just the tip of the iceberg…
How Circadian Rhythms Can Enhance Medication Effectiveness
As Lynne’s curiosity about circadian rhythms deepened, she began exploring how this science extends beyond light and sleep, particularly in the realm of medicine. Through her research, she uncovered a fascinating field called circadian medicine, which looks at how the timing of medications and treatments can influence their effectiveness.
One striking example she discovered involved a chemotherapy drug used to treat glioblastoma, an aggressive form of brain cancer. Studies showed that the time of day a patient took the drug had a profound effect on its outcome. If the drug was administered in the morning, patients experienced a significant extension in survival—an additional month beyond the standard FDA-approved result. This kind of improvement, which could be as life-changing as it sounds, was just the beginning.
Lynne's exploration of this topic opened up a broader conversation among scientists, revealing that many treatments might be more effective—or have fewer side effects—when given at certain times of day. While it’s not a one-size-fits-all solution, the possibilities are clear: the timing of medication could transform how we manage everything from chronic conditions to serious diseases. Yet, the full potential of this approach is still in the early stages, with ongoing clinical trials seeking to unlock even more of these time-sensitive breakthroughs.
Understanding Chronotypes: How Our Bodies Have Multiple Internal Clocks
Many of us think about circadian rhythms as a single "inner clock" that governs our sleep-wake cycle. But in reality, there are multiple internal clocks in our bodies—trillions, in fact, with each cell having its own clock. This "symphony of clocks" operates under the guidance of a "master clock" located in the brain, which coordinates everything from our metabolism to our sleep patterns.
But not all of our clocks are in perfect sync. These clocks can tick at slightly different rates, making everyone’s rhythm a little unique. This is where chronotypes come in. They describe the differences in how our clocks tick. Some people are early birds, others are night owls, and many are somewhere in between. Our chronotype is determined by how fast or slow our internal clocks are, influenced by factors like light exposure and our natural tendencies.
So, how do you figure out your chronotype? It’s not as simple as observing your current habits since societal schedules often skew our natural rhythms. But if you have the luxury of time—say, on vacation—without the pressure of alarm clocks and set routines, you might get a clearer picture of when your body naturally wants to sleep and wake up.
Understanding your chronotype can lead to better self-care and performance, whether it's managing work schedules or optimizing sleep.
The Impact of Shift Work on Circadian Rhythms and Chronotypes
As modern life becomes increasingly demanding, many people find themselves working irregular hours or shifting between day and night schedules, which can significantly disrupt their circadian rhythms. This is especially true for shift workers, who often live against their internal clocks, making it a difficult and unhealthy balancing act. For example, night shift workers may be awake when their bodies naturally want to rest, eating and working during hours that are contrary to their biology.
When we work at night or have to adapt to varying schedules, our circadian rhythms suffer. Our internal clocks are deeply influenced by natural light cues, and in today’s society, many of us spend over 90% of our time indoors, limiting our exposure to these natural environmental cues. This constant misalignment can lead to serious long-term health consequences.
For those working night shifts, the consequences are particularly pronounced. Research shows that our bodies function optimally during the daylight hours, including our metabolism, which is closely linked to circadian rhythms. Eating during the night, as shift workers often do, disrupts this natural ebb and flow. Metabolic processes are less efficient, and this misalignment has been associated with a higher risk of chronic diseases such as diabetes, heart disease, and obesity.
While our circadian rhythms are biologically determined, they can be influenced by our environment and behavior. If you're naturally a night owl but are forced to wake up early for work or other commitments, you may find yourself drifting further into night owl tendencies, missing the light that helps recalibrate your internal clock. Over time, this can create a snowball effect, where artificial light at night keeps you up late, and missing out on morning light makes it harder to reset.
For shift workers, there’s some flexibility in adjusting your chronotype through strategic light exposure. However, it’s a tough challenge. The reality is that shift work demands a significant amount of sacrifice, which often leads to disrupted sleep patterns and health issues, such as elevated cortisol levels, weight gain, high blood pressure, and blood sugar problems. The more we try to fight our natural rhythms, the harder it becomes to maintain balance and overall well-being.
The Link Between Hormones and Circadian Rhythms in Midlife
Science has come a long way in understanding the relationship between circadian rhythms and hormones. We now know that circadian rhythms themselves play a significant role in driving hormonal fluctuations throughout the day.
For women, the hormonal shifts that occur during perimenopause and menopause are particularly notable. Estrogen, in particular, is crucial for maintaining robust circadian rhythms. As women enter midlife and go through perimenopause and menopause, estrogen levels naturally decrease, and this reduction can "dampen" the circadian rhythms, meaning that the natural highs and lows of hormones become less pronounced. For instance, melatonin, the hormone that helps regulate sleep, no longer rises and falls with the same amplitude. This can make it harder to get energized in the morning and easier to feel fatigued during the day.
This dampening of circadian rhythms can have significant consequences. For example, many women experience increased sleep disturbances, changes in appetite, and a rise in the risk for metabolic diseases around this time. These shifts in hormonal regulation may at least partly explain why women become more susceptible to sleep issues and metabolic problems as they age.
So what can we do to get more in sync with our circadian rhythms and improve our overall well-being?
Lynne suggests focusing on three simple yet effective strategies, which she calls the Three C's. By implementing these, we can optimize our daily routines, improve sleep quality, and support our health, especially during midlife.
Three Key Strategies for Aligning with Your Circadian Rhythms:
Contrast:
Brighten your mornings: Try getting outside for at least 10 minutes, even on cloudy days. Natural light, especially blue light, is crucial in signaling to your body that it’s daytime.
Darken your evenings: At the end of the day, turn off overhead lights and opt for softer, warmer lighting—such as electric candles or table lamps. This signals to your body that it’s time to wind down for sleep.
Constrict:
Time-restricted eating: Aim to consolidate your eating window, ideally within 10 hours during daylight hours. This aligns with our evolutionary pattern of eating during the day and fasting overnight.
Consistency:
Go to bed and wake up at the same time every day: While it’s tough with work and weekend schedules, the more consistent you can be, the better. This reduces the jet-lag-like effects on your body when switching between weekdays and weekends.
By understanding and implementing the 3 C's, we can better align our lives with our natural rhythms, improving both our well-being and energy. For more tips and to connect with Lynne, check out her incredible resources here:
The Inner Clock: Living in Sync with Our Circadian Rhythms by Lynne Peeples