Scientists have discovered a gene that is responsible for your sleep patterns. So if you find your sleep cycle disrupted after a jet lag or a graveyard shift at work, it’s because Lhx1, the body’s timekeeper of sorts, is doing its job.
According to the scientists, both of Indian origin, the discovery of the gene is relevant for modern society where our sleep-wake cycles are disrupted by the schedules we choose to keep. They say the discovery can help in finding treatments for sleep problems, enabling shift-workers or jet-lagged travellers to adjust to time differences.
“We found a gene called Lhx1 that controls how individual clock neurons talk to each other. Such cross-talk helps consolidate activity and sleep to the right time of the day and prevents the sleep time from wandering when the light or dark cycle changes. The study shows that weakening the cross-talk among clock cells can be an effective method to change sleep- or activity-time, which is particularly useful for people who work between day and night shifts, so that they can adjust their sleep-time easily when their work-shift changes. Nearly 10-15 per cent of the workforce in most countries are shift-workers. When they change from night to day shift or when they try to be ‘day active’ during the weekend, it is very difficult for them to readjust their sleep time. Consequently, they get less sleep, have reduced productivity and, in the long run, are predisposed to many chronic diseases. Finding a treatment to readjust sleeping time will hugely benefit them,” said Dr Satchidananda Panda, associate professor at the Salk Institute, in an email interview.
Dr Shubhroz Gill, researcher at Salk Institute and co-first author of the paper, which has been published in the journal eLife, further explained that humans have internal biological clocks that generate 24-hour rhythms for sleep, waking hours and to maintain body temperature, among other things.
“The internal clock is useful only when it is in sync with the external clock, that is the day or night cycle. When a person travels from one time-zone to another, say, from San Diego to Mumbai, as soon as he or she lands in Mumbai, the internal clock is still running on San Diego time and is thus not very useful. As a result, it is realigned to Mumbai time, a process that takes a few days. In the meantime, the person undergoes the well-known adverse effects…namely, jet lag. We found that Lhx1 was involved in keeping the internal clock, a region of the brain called the suprachiasmatic nucleus (SCN) ticking normally when the person was in San Diego, and played a role in allowing the internal clock to resynchronise to Mumbai time. Lhx1 plays a critical role in the rhythm generation ability of the SCN,” he said.
The scientists disrupted the light-dark cycles in mice and compared changes in the expressions of thousands of genes in the SCN with other mouse tissues. In the end, they identified 213 gene expression changes that were unique to SCN. They then further narrowed these down to 13. Of these, only one was suppressed in response to light, the Lhx1.
The team has been working on this paper for six years and the research involved multiple methods, including genomics, genetics, electrophysiology, gene cloning, animal behavior and transgenic animals.
While Panda grew up in Bhubaneswar, Orissa, and left India for a PhD in the US, Gill, an IIT Kharagpur graduate, has been a postdoctoral researcher in Dr Panda’s group since 2012.