Night shifts and jet lag disrupt genetic rhythm
A new study from the UK finds that when we shift our sleep time, it disrupts the daily rhythms of our genes. Researchers from the University of Surrey report their findings in a study to be published in the Proceedings of the National Academy of Sciences.
The study also shows that some genes follow sleep-wake cycles, and some are regulated by central body clocks.
Senior author Derk-Jan Dijk, professor of Sleep and Physiology and director of Surrey's Sleep Research Centre, says:
"This research may help us to understand the negative health outcomes associated with shift work, jet lag and other conditions in which the rhythms of our genes are disrupted."
"The results also imply that sleep-wake schedules can be used to influence rhythmicity in many biological processes," he adds, "which may be very relevant for conditions in which our body clocks are altered, such as in ageing."
Night shift working linked to range of health problems
Working a night shift is classed as a "probable human carcinogen" because of evidence linking it to a range of health problems and diseases.
For this new study, the team invited 22 participants to spend time in a controlled environment without a natural light-dark cycle.
They put the participants on a 28-hour day pattern, which progressively delayed their sleep-wake cycle by 4 hours per natural day until their sleep was 12 hours of of sync with their brain clock and occurred in the middle of what would otherwise have been their normal daytime.
From blood samples collected from the participants the researchers were able to analyze what was happening to the rhythms of gene expression under this shifted sleep-wake pattern.
Six-fold reduction in rhythmic gene expression
They found a six-fold reduction in the number of genes that displayed a circadian rhythm (a pattern that follows an approximately 24-hour cycle).
These included many regulator genes involved with transcription and translation - which would indicate widespread disruption to many biological processes.
Genes involved with transcription and regulation - the transcriptome - interpret the DNA code for making proteins and controlling cell behavior.
Thus the results of the study suggest that disruption of our sleep-wake cycle interferes profoundly with the rhythm of genes that switch other genes on and off and fine-tune the biological processes in our bodies.
Co-author Dr. Simon Archer, a reader in Chronobiology at Surrey, says:
"Over 97% of rhythmic genes become out of sync with mistimed sleep and this really explains why we feel so bad during jet lag, or if we have to work irregular shifts."
A grant from the UK's Biotechnology and Biological Sciences Research Council (BBSRC) helped finance the study.
Written by Catharine Paddock PhD
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