Work Stress? DNA to Blame for Poor Tolerance to Shift Work

A new study revealed that your DNA plays a crucial role on how easily a person could adopt to constant disruptions of daily rhythms caused by work shifts.

The study, published in the journal Sleep, showed for the first time the genetic factors underlying poor tolerance to shift work. The study highlights the link between job-related exhaustion experienced by shift workers and a common variation in the melatonin receptor 1A (MTNR1A) gene.

For the study, the researchers analyzed Finnish shift workers from different lines of work. The researchers contrasted differences in the job-related exhaustion reported by employees with the generic differences in their entire genomes.

The researchers discovered a link between a common variation in the melatonin receptor 1A (MTNR1A) gene and the job-related exhaustion reported by shift workers. The researchers first found the link in a group of 176 shift workers included in the national Health 2000 survey. The association between the MTNR1A and job-related exhaustion of shift workers was further established in a group of 577 shift workers covering rest of the shift workers from the Health 2000 survey.

The researchers noted that the risk variation of the MTNR1A gene is probably related the methylation of DNA in the regulatory sequence of the MTNR1A gene as well as the weaker expression of the MTNR1A gene.

As a result of this variation, the risk variant of the gene can result to smaller number of melatonin receptors, causing weaker melatonin signaling. The melatonin signaling is one of the regulatory mechanisms in stabilizing the circadian rhythm. As previously accepted, shift works also disrupt circadian rhythm , leading to sleep disorders and daytime fatigue.

With their findings, the researchers claim that the influence of the risk variant of the MTNR1A gene may only explain the degree to which light exposure at night disrupts the circadian rhythm of shift workers at night.

 "The variant we have now discovered can only explain a small part of the variation between individuals, and it cannot be used as a basis to determine a person's tolerance to shift work," explained lead author Professor Tiina Paunio, from University of Helsinki, in a press release.