Mental health definitely has some level of seasonality to it. For example, seasonal affective disorder, or SAD, is common condition that can alter a person's mood by the season. Turns out humans aren't that different than a hibernating bear—we also tend to feel more depressed and grumpy during winters, when we don't get enough sunlight and spend too much time indoors.

But when it comes to most major mental health illnesses, researchers and clinicians have, to this point, had no effective way to monitor the seasonal patterns.

That was until the pioneering Google search engine began catering to user-searches, revealing more than what the eye—even a researcher's trained eye—could see. A new study shows that the search engine has created a way for scientists to survey the population's mental illness.

According to researchers, the number of searches for all major mental illnesses follow a seasonal pattern. Specifically mental illnesses soar during the winter season.

"The Internet is a game changer," said John Ayers, lead investigator and professor at the Graduate School of Public Health at San Diego State University. "By passively monitoring how individuals search online we can figuratively look inside the heads of searchers to understand population mental health patterns."

The study that will be published in the American Journal of Preventive Medicine in May, provided scientists with a new way to track a range of mental problems, something that was previously challenging and typically unsuccessful with methods like telephone surveys. This approach provides a clearer picture, rather than calling individuals who would be disinclined to talk about their mental well-being.

During summer, the study found that eating disorder searches were down by 37 percent in the United States, while searches for attention-deficit hyperactivity disorder, ADHD, declined by 28 percent. Searches for bipolar disease and obsessive-compulsive disorder, or OCD, were both down 18 percent, as well.

Searches related to suicide decreased 24 percent in the summer time; on the other side of the spectrum, searches for anxiety and related terms had the smallest drop of all, falling by a scant 7 percent.

For disorders like SAD, the transition into colder and darker fall and winter seasons drastically change an individual's moods. The person could experience depression, anxiety and fatigue. Major depression and mental disorders observed in this study were previously untraceable during seasons, now it could be tracked.

"It is very exciting to ponder the potential for a universal mental health emollient, like Vitamin D (a metabolite of sun exposure)," Ayers said. "But it will be years before our findings are linked to serious mental illness and then linked to mechanisms that may be included in treatment and prevention programs."

According to the Mayo Clinic, more than 26 percent of Americans over the age of 18 are diagnosed with a mental disorder in a year, so figuring out these patterns could be a true boon to the overall health of the country. Researchers still have to ponder whether the patterns could be explained through biology, environmental, or social stimulants.

"Our findings can help researchers across the field of mental health generate additional new hypotheses while exploring other trends inexpensively in real-time," said Benjamin Althouse, researcher and doctoral candidate at Johns Hopkins Bloomberg School of Public Health. "For instance, moving forward, we can explore daily patterns in mental health information seeking," Althouse added, "maybe even finding a 'Monday effect.' The potential is limitless."