A study in the current issue of Biological Psychiatry breaks new ground on the neurological differences between different types of insomnia. According to research, structural brain connectivity-different regional brain wiring-is indeed different between four of five subtypes of insomnia. Such findings might one day result in more focused approaches to treating people with insomnia, tailored toward their specific brain characteristics.
However, a large part of the population is affected by it, since, as one source reports, 10% of adults in Europe report sleeplessness. People suffering from insomnia describe difficulties in falling asleep, maintaining sleep, or waking too early and, consequently, experience severe disturbances to their normal functioning. Besides discomfort, insomnia is known to be associated with other health issues of higher risk, including cardiovascular problems, obesity, and psychological disorders such as depression and anxiety. In most cases, the application of cognitive behavioral therapy can treat insomnia; however, this does not work for everyone even when medication is combined with its use.
More insight into brain mechanisms is thought to better personalize treatments for insomnia. Past neuroimaging studies had suggested some promise for disruptions in large-scale brain networks such as the default mode network and salience network for this sleep disorder. The findings have been far from consistent, however. One reason may be the incredible variability between those with insomnia-a condition that may not lend itself to one-size-fits-all causes or treatments.
Recently, scientists discovered five different subtypes of insomnia that have their unique profile both in distress levels and personality traits. The subtypes are established not only by sleep patterns but also in a data-driven approach. Thus, the present study addressed the question of whether the subtypes also differ in brain structure. If such structural differences could be identified, new avenues toward more personalized treatment approaches could arise.
"When we began to consider subtypes many years ago, we felt that perhaps different constellations of minor deviations (at the flanks of the normal distribution) within circuits in the brain might have a final common pathway of a brain vulnerable to insomnia. At that time, there was no large database with MRI data in people with insomnia. Therefore, we tried to assess proxy measures for individual differences in brain circuits, said Eus van Someren, professor at the Netherlands Institute for Neuroscience and author of this study.
"We chose many hundreds of life history, mood, and personality trait questionnaires that had previously been linked to individual differences in brain circuits. We placed them on our website 'slaapregister.nl' and asked volunteers to complete them. Thousands of people filled out the long list of questionnaires. We applied data-driven clustering techniques to find particular profiles of scores on the questionnaires within the people that suffered from insomnia."