A slow start to the day, difficulty concentrating on daily tasks and the lethargy that comes with only a few hours of sleep. These are symptoms that anyone who suffers from insomnia will recognize.
But according to research, not all sleepless nights are the same. Brain scans have shown evidence of different types of insomnia, each with an associated pattern of neural wiring.
And while the clinical distinction may mean little to those suffering from sleep deprivation, the discovery does offer the potential for tailored interventions for people with different forms of insomnia, which could lead to better treatments.
Researchers at the Netherlands Institute for Neuroscience in Amsterdam analyzed MRI scans of more than 200 people suffering from insomnia and dozens of people who fell asleep soundly. They discovered structural changes that distinguished sleepers from insomniacs and five different types of insomnia.
“If these subtypes differ in their biological mechanisms, then patients in each subtype may benefit from different targeted treatments,” said Tom Bresser, neuroscientist and first author of the study.
Insomnia is broadly defined as poor sleep, generally resulting from difficulty falling asleep or staying asleep, which negatively impacts daytime functioning. About one-third of adults in Western countries experience sleep problems at least once a week, with up to 10% qualifying for a formal diagnosis of insomnia.
Chronic insomnia is diagnosed when someone has trouble sleeping at least three nights a week for three months or longer. The condition is almost twice as common in women as in men.
Doctors recommend going to bed and waking up at the same time every day, exercising daily, relaxing for at least an hour before bedtime, and making sure the bedroom is dark and quiet. Avoiding large meals late at night and not smoking or drinking alcohol or caffeine for at least six hours before bedtime also helps.
In the last work, published in Biological psychiatry and led by Prof Eus van Someren, the team looked at MRI brain scans of 204 people with insomnia who had been grouped according to the subtypes. The scans revealed differences in brain structure between the subtypes, providing further evidence that they are rooted in biology.
The researchers believe that personality and mood traits can be used to categorize insomnia because their impact can be similar during sleep and waking hours. For example, if people tend to be severely affected by stress in daily life, stress may also be more likely to disrupt their sleep.
For example, it means that meditation, an effective relaxation technique, may help subtypes characterized by high energy levels before bed. Patients with certain types of insomnia are more likely than others to develop depression, so clinicians could offer these individuals early preventive therapy.
Prof Tsuyoshi Kitajima, who studies sleep at Fujita Health University in Japan, said it was surprising that subtypes of insomnia derived from questionnaires had such biological differences in the brain scans. “I think this study provides significant evidence for the validity of the authors’ subtyping,” he added.
Dieter Riemann, a professor of clinical psychophysiology at the University of Freiburg in Germany, called the work “very interesting” and said it could encourage clinicians to take insomnia more seriously. “Many of them see insomnia as a minor complaint or a symptom, but if it has a neurobiological basis, that means we have to take insomnia more seriously than we used to,” he said.