After a long flight or a shift in schedule, many people experience persistent fatigue and a feeling of being out of sync with the local day. This discomfort, known as jet lag, stems from the disruption of our internal clock. This biological mechanism, which naturally regulates sleep and wake phases on a roughly twenty-four-hour cycle, then struggles to adjust when the time difference is significant.
To facilitate this resynchronization, exposure to bright light or taking melatonin are commonly recommended. However, these approaches require application at very specific times, and their results can vary between individuals. The demands of daily life also make these methods inconvenient, reducing their benefit for travelers or professionals with irregular schedules.
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Facing these limitations, a team of Japanese scientists has identified an oral compound named Mic-628. This molecule has the particularity of modifying the biological clock without being strictly dependent on the time it is ingested. It therefore represents a promising lead for a chemical approach aimed at mitigating the effects of jet lag.
Its mechanism of action is based on the activation of a key gene, Period1. Mic-628 binds to a protein called CRY1, which normally functions to repress this gene. This interaction releases the expression of Period1, a phenomenon that occurs simultaneously in the brain's master clock and in the peripheral clocks scattered throughout the body.
During experiments conducted on rodents, administering a single dose of Mic-628 helped reduce the adaptation period to an artificially induced jet lag. While this process usually requires seven days, it was here reduced to four days. This stable and unidirectional advance marks an original pathway for regulating biological rhythms.
Scientists see Mic-628 as a prototype for a new family of drugs targeting circadian disorders. Additional work on animals, and then on humans, is needed to evaluate its safety and efficacy. These results, published in the
Proceedings of the National Academy of Sciences, lay promising groundwork for future medical applications.
The role of the circadian clock in our body
Our body houses a master internal clock, nestled in a region of the brain called the hypothalamus. This command center follows a cycle close to twenty-four hours and influences a multitude of physiological functions. It controls not only the sleep-wake cycle, but also body temperature or the production of hormones like cortisol and melatonin.
This central clock also coordinates peripheral clocks present in various organs, such as the liver or the heart. Together they form a harmonized network that allows the body to align with the day-night cycle. Disruptions to this system frequently occur during transmeridian travel or shift work, leading to sleep difficulties and impaired alertness.
Its operation relies on the rhythmic expression of specific genes, including Period and Cryptochrome. Their activity oscillates throughout the day, creating a feedback loop that sustains the rhythm. External signals, primarily light, can readjust this mechanism to tune it to the environment, but this operation usually takes several days.
Understanding this system is therefore necessary to devise interventions capable of correcting its misalignments. Ongoing research explores chemical or behavioral ways to act on these genes and accelerate readaptation, which could benefit people regularly facing jet lag or sleep disorders related to their professional activity.