The sluggish start to the day, the difficulty concentrating on everyday tasks and the lethargy that comes with only a few hours of sleep, these are the symptoms that will be familiar to anyone who suffers from insomnia.
But according to research, not all sleepless nights are the same. Brain scans have revealed evidence for different forms of insomnia, each with an associated pattern of neural wiring.
And while the clinical distinction may mean little to those whose days are plagued by sleep deprivation, the discovery does raise the prospect of tailored interventions for people with different types of insomnia, which could lead to better treatments.
Researchers at the Netherlands Institute for Neuroscience in Amsterdam analyzed MRI scans of more than 200 insomniacs and dozens of healthy sleepers and noted structural changes that distinguished sleepers from insomniacs and five distinct forms of insomnia.
“If these subtypes differ in their biological mechanism, patients in each subtype may benefit from different focused treatments,” says Tom Bresser, a neuroscientist and first author of the study.
Insomnia is broadly defined as poor sleep, usually due to difficulty falling or staying asleep, which negatively affects daytime functioning. About a third of adults in Western countries have sleep problems at least once a week, with up to 10% qualifying for a formal insomnia diagnosis.
Chronic insomnia is diagnosed if someone has trouble sleeping on at least three nights a week for three months or more. The condition is almost twice as common in women as men.
Doctors recommend going to bed and waking up at the same time every day, exercising daily, relaxing at least an hour before bed and making sure the bedroom is dark and quiet. Avoiding large meals late at night and not smoking or drinking alcohol or caffeine at least six hours before bed also help.
In the latest work, published in Biological Psychiatry and led by Prof Eus van Someren, the team looked at MRI brain scans of 204 people with insomnia grouped according to the subtypes. The scans revealed brain structure differences between the subtypes, providing further evidence that they are rooted in biology.
The researchers think personality and mood traits can be used to categorize insomnia because their influence can be similar during sleep and waking hours. For example, if people tend to be severely affected by stress during daily life, stress may also be more likely to interfere with their sleep.
This means, for example, that meditation, an effective relaxation technique, can help with subtypes characterized by high energy levels before bedtime. Patients with some forms of insomnia are more likely than others to develop depression, so clinicians can offer early preventive therapy to these individuals.
Prof Tsuyoshi Kitajima, who studies sleep at the Fujita Health University in Japan, said it is surprising that insomnia subtypes derived from questionnaires have 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 “highly 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 underpinning, it will mean that we need to take insomnia more seriously than we did before,” he said.
