Summary: Researchers uncovered how our biological clocks keep a 24-hour rhythm even as temperatures fluctuate. Using physics-based models, they discovered that at higher temperatures, gene activity rhythms become distorted—rising faster and falling slower—to maintain the cycle’s duration.
This waveform distortion also influences how well our clocks sync with light-dark cues, keeping us aligned with day and night. The findings may help explain sleep disorders, jet lag, and aging-related changes in our internal clocks.
Key Facts:
- Waveform Distortion: Rhythms skew at higher temperatures to maintain timing.
- Sync Stability: Distortion helps the clock resist irregular light-dark cycles.
- Potential Biomarker: May explain sleep disorders and individual clock differences.
Source: RIKEN
Researchers led by Gen Kurosawa at the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) in Japan have used theoretical physics to discover how our biological clock maintains a consistent 24-hour cycle—even as temperatures change.
They found that this stability is achieved through a subtle shift in the “shape” of gene activity rhythms at higher temperatures, a process known as waveform distortion. This process not only helps keep time steady but also influences how well our internal clock synchronizes with the day-night cycle.
The study was published in PLOS Computational Biology on July 22.
Have you ever wondered how your body knows when it’s time to sleep or wake up? The simple answer is that your body has a biological clock, which runs on a roughly 24-hour cycle.
But because most chemical reactions speed up as temperatures rise, how our bodies compensate for changing temperatures throughout the year—or even as we move back and forth between the outdoor summer heat and indoor air-conditioned rooms—has remained largely a mystery.
Our biological clock is powered by cyclical patterns of mRNA—the molecules that code for protein production—which result from certain genes being rhythmically turned on and off.
Just as the back and forth of a swinging pendulum over time can be described mathematically as a sine wave, smoothly going up and coming down over and over, so can the rhythm of mRNA production and decline.
Kurosawa’s research team at RIKEN iTHEMS and a collaborator at YITP, Kyoto University, drew on theoretical physics to analyze the mathematical models that describe this rhythmic rise and fall of mRNA levels.
Specifically, they used the renormalization group method, a powerful approach adapted from physics, to extract critical slow-changing dynamics from the system of mRNA rhythms.
Their analysis revealed that at higher temperatures mRNA levels should rise more quickly and decline more slowly, but importantly, the duration of one cycle should stay constant. When graphed, this high-temperature rhythm looks like a skewed, asymmetrical waveform.
But does this theorized change actually happen? To test this theory in real organisms, the researchers examined experimental data from fruit flies and mice. Sure enough, at higher temperatures, these animals showed the predicted waveform distortions, confirming that the theoretical predictions align with biological reality.
The researchers conclude that waveform distortion is the key to temperature compensation in the biological clock, specifically the slowing down of mRNA-level decline during each cycle.
The team also found that waveform distortion affects how well the biological clock synchronizes with environmental cues, such as light and darkness. The analysis predicted that when the waveform becomes more distorted, the biological clock is more stable, and environmental cues have little effect on it.
This theoretical prediction matches experimental observations in flies and fungi and is significant because irregular light-dark cycles are part of modern-day life for most people.
“Our findings show that waveform distortion is a crucial part of how biological clocks remain accurate and synchronized, even when temperatures change,” says Kurosawa.
He adds that future research can now focus on identifying the exact molecular mechanisms that slow down the decline in mRNA levels, which leads to the waveform distortion.
Scientists also hope to explore how this distortion varies across species—or even between individuals—since age and personal differences may influence how our internal clocks behave.
“In the long term,” Kurosawa notes, “the degree of waveform distortion in clock genes could be a biomarker that helps us better understand sleep disorders, jet lag, and the effects of aging on our internal clocks. It might also reveal universal patterns in how rhythms work—not just in biology, but in many systems that involve repeating cycles.”
About this circadian rhythm research news
Author: Masataka Sasabe
Source: RIKEN
Contact: Masataka Sasabe – RIKEN
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Waveform distortion for temperature compensation and synchronization in circadian rhythms: An approach based on the renormalization group method” by Gen Kurosawa et al. PLOS Computational Biology
Abstract
Waveform distortion for temperature compensation and synchronization in circadian rhythms: An approach based on the renormalization group method
Numerous biological processes accelerate as temperatures increase, but the period of circadian rhythms remains constant, known as temperature compensation, while synchronizing with the 24h light-dark cycle.
We theoretically explore the possible relevance of waveform distortions in circadian gene-protein dynamics to the temperature compensation and synchronization.
Our analysis of the Goodwin model provides a coherent explanation of most of temperature compensation hypotheses.
Using the renormalization group method, we analytically demonstrate that the decreasing phase of circadian protein oscillations should lengthen with increasing temperature, leading to waveform distortions to maintain a stable period.
This waveform-period correlation also occurs in other oscillators like Lotka-Volterra, van der Pol models, and a realistic model for mammalian circadian rhythms.
A reanalysis of known data nicely confirms our findings on waveform distortion and its impact on synchronization range.
Thus we conclude that circadian rhythm waveforms are fundamental to both temperature compensation and synchronization.
