Insomnia is currently the second more common mental disorder affecting 10% of adults and 22% of elderly people. Insomnia is characterized by a difficulty falling asleep or staying asleep and is followed by sleepiness and low energy during the day time. Insomnia can be caused by stress, chronic pain, restless leg syndrome, heart problems, and certain medications. Insomnia is also a risk factor for many other diseases including heart disease, depression, and obesity. Genetics seems to play a role in the disorder as 38% of the disease in males and 59% in females can be attributed to heritable factors that you got from your parents. A limited number of studies have been done trying to find what these genetic factors are and most of them have a limited number of subjects. To understand the genetic component of the disease better, a team of researchers from the Netherlands recruited over 113,000 people and measured how variations in their genes associated with insomnia symptoms.
In this study, published in Nature Genetics, the researchers collected DNA from the blood of 113,006 people and quantified all the different variations in all the genes. Using this data, they determined how associations in certain genes were associated with symptoms and complaints of insomnia. Doing this analysis highlighted mutations in one gene, MEIS1, that was the most significantly associated with insomnia. MEIS1 is important in the development of the body in utero and has been associated with restless leg syndrome in the past. In this study, the association of MEIS1 with insomnia was not related to restless leg syndrome in the population and so the researchers could be certain that variation in this gene was associated with insomnia. Additionally, the researchers found that there were significant sex differences in the variations that were associated with insomnia in males and females. This result suggests that the genetic alterations that lead to insomnia may be different in males and females but the study was underpowered to determine this for sure. Finally, the team determined that genetic abnormalities in people with insomnia overlapped with other disorders including: anxiety disorder, depressive symptoms, cigarettes per day, and type-2 diabetes. These genetic abnormalities were also negatively associated with feelings of well being, educational attainment, and childhood intelligence. This means that people with genetic alterations associated with insomnia were more likely to smoke, have type-2 diabetes, and anxiety and were less likely to fell good about themselves or attain higher education.
This research is an important first step to understanding how insomnia begins and how to best treat it. Finding appropriate treatments for insomnia will not only help improve the sleep quality for sufferers but also help improve overall health. These results will need to be replicated in other studies and basic science will need to help us understand how MEIS1 plays a role in sleep disorders.
Photo Credit: Flickr Craig Sunter