Insomnia, depression, and anxiety are among the most common mental health issues worldwide. Many people struggle with more than one of these conditions at the same time, and even when treatment helps, symptoms often return later. This has led scientists to wonder: could these disorders be connected by a common problem in the brain?
A new study from researchers at Vrije Universiteit Amsterdam offers important clues. The team, including Siemon de Lange, Elleke Tissink, and Eus van Someren, looked at brain scans from more than 40,000 people in the UK Biobank to understand what happens in the brain in these three conditions. Their findings were recently published in Nature Mental Health.
Tissink explains that their lab studies what is shared and what is different among insomnia, anxiety, and depression. While some researchers focus on genetics, this team focused on brain structure and function. They wanted to know: are there common patterns in the brain that could explain why these disorders often appear together?
The study found some important overlaps. In all three conditions, people had a smaller surface area of the brain’s outer layer—the cerebral cortex—along with a smaller thalamus (a deep brain structure that helps process information and regulate sleep) and weaker connections between different parts of the brain.
These similarities suggest that the disorders may share a common root in the brain’s structure and how its different parts communicate.
At the same time, the researchers also saw differences. Insomnia seemed more strongly linked to changes in brain areas involved in reward, such as smaller volumes in those regions. Depression was more tied to thinning in brain areas that help with language and emotion.
Anxiety, on the other hand, was connected to lower activity in the amygdala—a brain area involved in processing fear—and weaker communication in areas that rely on chemicals like dopamine and glutamate, which help brain cells send messages.
Even though these areas are different, the team discovered something surprising: they all belong to the same larger brain circuit.
This circuit includes the amygdala, hippocampus, and medial prefrontal cortex—regions that together play important roles in emotion, memory, and decision-making. The researchers believe that this shared brain circuit might be a key part of what makes someone more vulnerable to all three disorders.
This is the first time such a large study has looked at insomnia, depression, and anxiety together in this way. The results suggest that instead of treating each condition separately, future therapies could target this shared brain circuit. That might help explain why, for example, treating insomnia sometimes also improves symptoms of depression.
Tissink adds that better understanding this brain circuit could lead to new kinds of treatments that work more effectively for people suffering from multiple mental health challenges. The study not only highlights the deep connections between these disorders but also opens up new paths for research and care.
In summary, this research shows that while insomnia, depression, and anxiety have their own features, they also share a common brain pathway. This insight could help explain why these disorders so often go hand in hand—and why treating one may sometimes help with the others.
If you care about health, please read studies that scientists find a core feature of depression and this metal in the brain strongly linked to depression.
For more information about health, please see recent studies about drug for mental health that may harm the brain, and results showing this therapy more effective than ketamine in treating severe depression.
The research findings can be found in Nature Mental Health.
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