A new study from King’s College London suggests that shift work may speed up muscle aging by disrupting the body’s natural clocks. Most of us know that the human body runs on a natural 24-hour cycle, called the circadian rhythm, which regulates our sleep, energy levels, and even digestion.
But what many people don’t realize is that each cell in the body, including muscle cells, has its own internal clock. These tiny timekeepers help manage important tasks like protein repair and muscle growth, especially while we sleep.
The research, published in the Proceedings of the National Academy of Sciences, found that this internal clock in muscle cells is vital for keeping our muscles healthy. At night, when we are resting, the muscle clock triggers a process that breaks down old or damaged proteins.
This helps to keep muscles strong and functioning well. Disrupting this cycle, as often happens with shift work, can stop this repair process from happening properly, leading to faster muscle breakdown as we age.
The study was led by Jeffrey Kelu, a research associate at King’s College London. To understand how this works, Kelu and his team experimented with zebrafish, a small fish species often used in scientific studies because their genes are surprisingly similar to humans.
About 70% of zebrafish genes are identical to human genes, making them ideal for studying how biological processes work. Another advantage is that zebrafish are transparent, so researchers can easily observe their muscles under a microscope.
To study the impact of disrupted circadian rhythms, the researchers altered the muscle clocks in the zebrafish by overexpressing a faulty clock protein. They monitored the fish for two years, comparing them to normal fish. At younger ages, around six months and one year, there were no noticeable differences in muscle size between the two groups.
But at two years old, the zebrafish with disrupted muscle clocks showed clear signs of premature aging. They were smaller, weighed less, swam less often, and moved more slowly. These are all typical signs of muscle aging, known as sarcopenia, which is also seen in humans.
To understand why this happened, the researchers looked deeper into what goes on inside the muscles. Normally, the muscle clock regulates a process called protein turnover. Throughout the day, as we move and exercise, tiny bits of muscle tissue get damaged and need to be repaired.
At night, while we sleep, the muscle clock helps break down these damaged proteins and replaces them with new ones. This repair work is crucial for maintaining muscle strength and function. When the muscle clock is disrupted, the damaged proteins build up instead of being cleared away, weakening the muscles over time.
Dr. Kelu explained that about four million people in the UK work shifts, keeping businesses and emergency services running around the clock. His team’s findings add to the growing evidence that working irregular hours can harm various aspects of health, including muscle strength.
By understanding how these disruptions affect the body, researchers hope to develop treatments that could slow down or even prevent the muscle aging process in shift workers.
The team is already exploring ways to use circadian biology to fight muscle decline. Preclinical trials are currently testing drugs that target specific clock proteins to see if they can restore proper muscle function. These early studies suggest that it may be possible to help shift workers maintain stronger muscles, even if their work schedules disrupt their sleep patterns.
Professor Simon Hughes, who co-authored the study, emphasized how much scientists can learn from studying simple organisms like zebrafish. He noted that while these findings are promising, it’s important to confirm them in human studies. However, the results do show scientists where to look next and could lead to new therapies for muscle aging in the future.
This study is an important step in understanding why shift work seems to age the body faster. It also suggests that by taking care of our body clocks—both in our brains and our muscles—we might be able to slow down some of the aging processes that come with irregular sleep and work schedules.
For the millions of people who work through the night, this could be a path to better health and stronger muscles as they age.
If you care about muscle, please read studies about factors that can cause muscle weakness in older people, and scientists find a way to reverse high blood sugar and muscle loss.
For more health information, please see recent studies about an easy, cheap way to maintain muscles, and results showing these vegetables essential for your muscle strength.
The research findings can be found in PNAS.
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