Sleep disorders change the structure of the brain

The researchers compared two large classes of disorders: dissomnias (such as insomnia and sleep apnea, where a person has difficulty falling asleep or staying asleep) and parasomnias (such as sleepwalking, nightmares, and night terrors, where the sleep cycle itself is disrupted). This comparative approach allowed them to identify both common changes across all disorders and unique features of individual groups.

A key finding was the reduction in the volume of the thalamus, a crucial brain region responsible for filtering information, maintaining focus, and enabling higher cognitive functions. Particularly pronounced changes were recorded in the pulvinar, a part of the thalamus that helps to manage attention and cognitive control. These structural shifts affect entire brain networks associated with task performance and reaction time. This explains the typical consequences of poor sleep, such as slower responses, impaired decision-making abilities, and an increased risk of errors and accidents.

However, parasomnias have their own unique characteristics. People with these disorders have been found to have changes in the posterior cingulate cortex, an area involved in motivation, decision-making, and emotional regulation. It is likely that these shifts are responsible for the changes in mood, behavior, and emotional control that sometimes accompany parasomnias. However, experts have not been able to identify specific structural changes that are unique to insomnia. This suggests that different types of sleep disorders may have different effects on the brain, depending on the specific stage of sleep that is disrupted.

According to the authors of the work, most studies have previously examined individual disorders in turn, and combining data from many studies has allowed them to see common patterns that are important for developing more accurate diagnostic methods and personalized treatment approaches. The researchers also want to further study specific parasomnias, such as sleepwalking and REM behavior disorder, and determine whether the changes they have found are the cause or consequence of the disorders.