Irregular sleep may cause premature muscle aging

Time often influences how we feel physically, affecting muscle function, whether it’s waking up with a jolt or unwinding at the end of a long day. Researchers studying the body’s natural cycles have begun to link disruptions in our sleep schedules to accelerated muscle aging.

The focus is on circadian rhythms and how they affect muscle health. This direction comes from work involving lead author Dr. Jeffrey Kelu, a research associate at King’s College London.

Dr. Kelu’s team explored the idea that internal muscle clocks might explain why irregular routines hasten the signs of getting older.

How muscle clocks affect aging

Circadian rhythms rely on biological “timekeepers” in different parts of the body. Scientists have long known that the brain and other organs use these clocks to regulate temperature, hormones, and digestion.

Research now suggests muscle cells run on their own schedule. When these cycles are interrupted, the aging process can ramp up, also known as sarcopenia, which is the gradual decline in muscle mass.

Muscle aging patterns in fish

“We then monitored the fish for two years, comparing them to healthy controls. While no significant differences were seen at younger ages, fish lacking a functional muscle clock eventually showed clear signs of premature aging,” said Dr. Kelu.

The team ran experiments on zebrafish, small aquarium fish that share many genes with humans. 

Scientists picked zebrafish partly because their transparent features make muscle changes easier to observe. These characteristics save valuable time and resources before trying similar work in larger animals or humans.

Observing long-term health impacts

Zebrafish aren’t just chosen for convenience. Their muscle structure and cellular processes are surprisingly similar to those in humans, which makes them a reliable model for studying complex biological systems like circadian rhythms and protein turnover.

Zebrafish also reproduce quickly and develop rapidly, which helps researchers observe long-term effects like aging within a much shorter period.

Because their bodies are transparent at early stages, scientists can watch what’s happening in real time, instead of relying solely on post-mortem tissue samples.

Sleep patterns and muscle aging

“In the UK, approximately four million shift workers play a vital role in keeping businesses and emergency services operational around the clock,” said Dr. Kelu.

“Our study provides further evidence that the disruption of circadian rhythms in shift workers compromises multiple aspects of health.”

Muscle decline in later years appears to be only one piece of the puzzle. Experts note that shift schedules disturb normal sleep-wake cycles and hamper body clocks for years.

This misalignment seems to speed up the same muscle wear-and-tear that shows up with age, leaving people more at risk of mobility issues.

What this means for everyday routines

These findings don’t just affect night-shift workers. People with irregular sleep patterns, long-haul travelers, or anyone who regularly stays up late may also experience similar disruptions to their internal clocks.

The disruptions can add up over time, even if obvious signs do not emerge right away. This raises questions about how much recovery the body truly gets when sleep schedules constantly change.

Sticking to a consistent bedtime and allowing for deeper rest at night may help the body carry out its normal muscle maintenance routines more effectively.

Muscle aging in men and women

Although the study used zebrafish, similar patterns have been seen in humans, especially when it comes to how muscle mass declines with age.

Recent population data suggests that men may experience sharper drops in muscle strength over time, which lines up with what was observed in male zebrafish.

This difference might come from how circadian rhythms interact with hormones and metabolic changes across the lifespan.

Further research is needed to investigate whether men and women need different strategies to protect muscle health as they get older.

Sleep’s influence on muscle aging

Healthy muscles go through daily cleanup. Faulty proteins gather during active periods and are cleared at night so muscles can recover.

Scientists discovered that circadian rhythms direct this cleanup. When these rhythms break, damaged proteins build up, making muscle tissue weaker over time.

New possibilities are emerging. Certain treatments that target internal clocks may help prevent the early muscle loss reported in night workers, though more trials are needed.

“This work shows how studying something as complicated as muscle growth in a simple system, like little fish larva, can really teach us something,” said Professor Simon Hughes, from King’s College London. Therapies that stabilize muscle clocks might keep cells healthier for longer.

Future of muscle aging treatments

Early-stage research is already testing drugs that target clock-related proteins like Rev-erb and Ror, which play a role in regulating nighttime muscle cleanup.

If these treatments prove safe and effective, they could become part of new therapies designed to slow or prevent sarcopenia in at-risk groups.

There’s also growing interest in chronomedicine, timing treatments to match the body’s natural rhythms. For muscle health, this might mean taking medications or scheduling physical therapy at specific times of day to get the best results.

The study is published in Proceedings of the National Academy of Sciences.

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