January 21, 2014
How Jetlag And Nightshift Wreak Havoc On Your Genes
Sleep and systems biology researchers from the University of Surrey found that jet lag or working the late shift could have a significant impact on health. Researchers placed 22 participants on a 28-hour day schedule, delaying their sleep-wake cycle by four hours each day until sleep occurred during the middle of the day. The team then collected blood samples to measure the participants' rhythms of gene expression.
The researchers wrote in the journal Proceedings of the National Academy of Sciences they found that during the disruption of sleep timing there was a six-fold reduction in the number of genes that displayed a circadian rhythm, which is the internal clock that regulates the body’s daily cycle.
“These rhythmic processes, together with posttranslational modification, constitute circadian oscillators in the brain and peripheral tissues, which drive rhythms in physiology and behavior, including the sleep–wake cycle. In humans, sleep is normally timed to occur during the biological night, when body temperature is low and melatonin is synthesized. Desynchrony of sleep–wake timing and other circadian rhythms, such as occurs in shift work and jet lag, is associated with disruption of rhythmicity in physiology and endocrinology,” the researchers wrote.
“However, to what extent mistimed sleep affects the molecular regulators of circadian rhythmicity remains to be established.”
The study revealed which genes are regulated by sleep-wake cycles and which are regulated by central body clocks.
“The results suggest that sleep-wake cycles affect molecular mechanisms which are at the core of the generation of circadian rhythms of gene transcription,” explained Professor Derk-Jan Dijk, who led the research, said in a statement. “This research may help us to understand the negative health outcomes associated with shift work, jet lag and other conditions in which temporal organization is compromised.”
Dijk said the findings imply that sleep-wake schedules can be used to influence bodily processes, which could be relevant for conditions in which circadian rhythmicity is altered.
“Over 97% of rhythmic genes became arrhythmic with mistimed sleep and this really underlines why we feel so bad during jet lag, or if we have to work irregular shifts,” said Dr Simon Archer, one of the leading authors of the research.
The team said they estimated the separate contribution of sleep and circadian rhythmicity and found the sleep-wake cycle coordinates the timing of transcription and translation in particular.
“The data show that mistimed sleep affects molecular processes at the core of circadian rhythm generation and imply that appropriate timing of sleep contributes significantly to the overall temporal organization of the human transcriptome,” the researchers wrote in the journal.