Do you have problems sleeping but you don't know why? A new study may provide some answers. Researchers have discovered specific genes that could make us more susceptible to insomnia.

What's more, the researchers—led by Murray Stein, of the University of California, San Diego—found that these genes may also be tied to mental health disorders and metabolic heath conditions.

Stein and team recently published the results of their study in the journal Molecular Psychiatry.

It is recommended that for optimal health and well-being, adults get around 7–9 hours of sleep every night.

However, many of us do not meet this recommendation; around 50–70 million adults in the United States have some form of sleep disorder, with insomnia being the most common.

Insomnia is characterized by trouble falling asleep or staying asleep. It is estimated that around 30% of adults in the US have short-term insomnia. Around 10% of US adults have chronic insomnia, which is defined as sleep problems that persist for at least 1 month.

Common risk factors for insomnia include stress, abnormal working patterns, and inactivity. The new study from Stein and colleagues, however, suggests that our genes could also play a role.

Insomnia genes linked to depression

The researchers came to their finding by analyzing the DNA samples of more than 33,000 soldiers who were a part of the Army Study To Assess Risk and Resilience in Service members.

The data were then compared with data from two other studies that included genetic information from UK Biobank, which is a health database of around 500,000 adults.

From their overall analysis, Stein and his colleagues identified a specific genetic variant located on chromosome 7—called q11.22—that was associated with the risk of insomnia. Among subjects of European descent, a certain variant in the gene RFX3—which is located on chromosome 9—was also linked to insomnia risk.

"Several of these variants rest comfortably among locations and pathways already known to be related to sleep and circadian rhythms," notes Stein.

Interestingly, the scientists found that the genetic variants for insomnia were "significantly positively correlated with major depressive disorder and type 2 diabetes."

They note that insomnia often co-occurs with depression and other mental health disorders, and the sleep disorder has also been linked to increased risk of type 2 diabetes. These new findings may have uncovered a genetic explanation for these associations.

Stein and colleagues conclude:

"Such insomnia-associated loci may contribute to the genetic risk underlying a range of health conditions, including psychiatric disorders and metabolic disease."