What Is Insomnia, and How Is It Related to Brain Structure?

Insomnia, also known as the inability to sleep, is a sleep problem. People with insomnia toss and turn in bed, cannot keep their eyes closed for more than a few minutes, and struggle to fall asleep.

Using an advanced MRI (Magnetic Resonance Imaging, commonly known as an MRI scan) technique, researchers examined the brains of patients with insomnia. They found certain abnormalities in the white matter of their brains. Radiology published this study; let us examine it together.

What Is Insomnia?

Primary insomnia can be described as a mild cognitive disturbance that sometimes makes sleeping difficult for days or even months, usually causes daytime fatigue from lack of sleep, and produces a feeling of low spirits. In some cases, insomnia may also present as depression and anxiety (worry and inner distress).

Insomnia is a remarkably common condition, but it has underlying causes and can sometimes be difficult to diagnose.

White matter in the brain consists of bundles of nerve-cell axons, or long nerve fibers, connecting one part of the brain to others. If these fibers are damaged or separated, communication between the brain regions linked by them is also impaired.

The study involved 30 volunteers and 23 patients diagnosed with insomnia. To identify and assess the psychological state and sleep patterns of the volunteers and patients, measures including the Pittsburgh Sleep Quality Index, Insomnia Severity Index, Self-Rating Anxiety Scale, and Self-Rating Depression Scale were administered.

All participants also underwent detailed MRI scans. These used MRI DTI (Diffusion Tensor Imaging), a special technique that allows detailed examination of water movement in the brain’s white matter and uses this movement to identify spaces between white-matter structures. The research used tract-based spatial statistics. This technique made more sensitive measurements possible.

The findings showed that, compared with healthy people, patients with insomnia had substantial white-matter disruptions and gaps, especially in the right cerebral hemisphere and thalamus, brain regions regulating sleep patterns, consciousness, and alertness. These damaged white-matter tissues generally have a significant negative effect on patients’ sleep, wakefulness, cognitive functions, and sensory-motor functions. Furthermore, abnormalities in the thalamus and the corpus callosum, the largest white-matter structure in the brain, directly affect the severity and duration of patients’ insomnia.

Another finding was that a hidden cause of white-matter abnormalities in patients with insomnia may be a deficiency of the myelin sheath, the structure wrapping around and protecting nerves, in this part of the brain.

The researchers recommend more detailed and extensive investigations to establish the relationship between white matter and insomnia, and draw attention to this issue.