In 2016, a study on mice found that certain sleep traits, like insomnia, have genetic underpinnings. Several studies of human twins have also suggested that insomnia can be an inherited trait. Now, new research published in Molecular Psychiatry not only reinforces that finding, but also suggests that there may be a genetic link between insomnia and some other psychiatric and physical disorders, like depression and type 2 diabetes, as Psych Central alerts us.
Insomnia is particularly prevalent in populations of military veterans. For this study, researchers at VA San Diego Healthcare System analyzed questionnaire responses and blood samples from almost 33,000 new soldiers at the beginning of basic training, along with pre- and post-deployment surveys from nearly 8000 soldiers deployed to Afghanistan starting in early 2012. They conducted genome-wide association tests to determine the heritability of insomnia and links between insomnia and other disorders. The results were adjusted for the presence of major depression (since insomnia is a common symptom of depression).
The genotype data showed that insomnia disorder was highly heritable and pinpointed potential genes that may be involved. The study indicated that there's a strong genetic correlation between insomnia and major depression. (The two were distinct, though, meaning that the insomnia couldn't be totally explained by the depression.) They also found a significant genetic correlation between insomnia and type 2 diabetes.
Because the study relied on data from the U.S. military, the study doesn't have the most far-reaching sample—it was largely male and wasn't as racially diverse as it could have been. (While it analyzed responses from recruits from European, African, and Latino ancestry, there weren't enough Asian-American participants to analyze as a group.) The responses were also self-reported, which isn't always the most accurate data-collection method.
The genes indicated by this study could be used to develop new treatments for insomnia, but future studies will likely need to explore these questions within broader populations.
[h/t Psych Central]