Jet lag is in the genes, scientists say
Scientists at the Salk Institute for Biological Scences have identified a master gene that controls sleep and wake cycles and that could explain why most people have a hard time adjusting their sleep cycles when traveling between time zones.
The gene, called Lhx1, could be the key to easing the experience of travelers and shift workers whose sleep interruption has been known to cause health problems in addition to discomfort.
"It's possible that the severity of many dementias comes from sleep disturbances," says Satchidananda Panda, a Salk associate professor who led the research team. "If we can restore normal sleep, we can address half of the problem."
Scientists have for a long time observed the existence of a region in the brain's hypothalamus that hosts over 20,000 densely packed neurons. It's called the suprachiasmatic nucleus (SCN) and it controls the body clock.
Each cell in the body runs on this clock, for protein levels dip and rise in time with the 24-hour body clock, also referred to as circadian rhythm.
Exposure to light resets the brunt of the SCN cells but not all of them, sending travelers into jet lag due to the imbalance between cells on the rhythm and cells who've tumbled off.
In the study, scientists experimented on mice, disrupting their cyclical exposure to light and dark and comparing changes in gene expressions within the SCN and in cells from other parts of their bodies.
They were able to identify 213 gene expression changes unique to the SCN and subsequently narrowed their focus to 13 of them that could control other genes.
Of this pool, they observed just one, Lhx1, that reacted to light exposure by shutting off.
"No one had ever imagined that Lhx1 might be so intricately involved in SCN function," says Shubhroz Gill, a postdoctoral researcher and co-first author of the paper.
The discovery marks the first time the gene, normally associated with proper neural development, has been singled out as a mastermind of the light-dark cycle.
"It was all about communication -- the neurons were not talking to each other without this molecule," says Ludovic Mure, a postdoctoral researcher and an author on the paper.
Potential developments stemming from the study include cell regenerative therapies that relieve sleep problems by restoring SCN cells.
The study was published in the journal eLife and gene expression data from the study is available through through a searchable web interface at scn.salk.edu providing a source on genes and light-dark cycles to other researchers and curious individuals.
