What’s the difference between someone who cannot fall asleep at night and someone who can? People with chronic insomnia show more plasticity — more adaptability to change — and also more activity in the motor cortex, the region of the brain that controls movement. “Insomnia is the most common disorder seen in clinics,” Dr. Rachel E. Salas, an assistant professor of neurology at the Johns Hopkins University School of Medicine, told Medical Daily. As Salas describes it, insomnia is not just a nighttime disorder but a 24-hour brain condition. “It’s like a car that’s always running or a light switch that’s always on,” she said. “With each person, there may be different factors causing and perpetuating it, so that makes it very difficult to treat. There’s a big need for research in this area.”
Lights on Across America
About one quarter of the U.S. population suffers from insomnia at some point in their lives, while almost one in ten people experience chronic insomnia. Although ongoing sleep loss has been linked to a number of diseases and conditions, including diabetes, cardiovascular disease, and depression, insomnia also causes sufferers to have more immediate problems with memory and concentration as its effects may appear almost immediately. “Patients with insomnia have been shown to have faster EEGs and higher cortisol levels,” Salas said. (EEG measures brain activity, and cortisol is a stress hormone) “In the field this is called hyper-arousal but I look at it more as a dis-regulation of arousal.” For this reason Salas decided, “Let’s look into the brain, let’s see what information we can get using biology.”
For her investigation, Salas and her team of researchers recruited 28 participants over the age of 50 — 18 suffering from insomnia and 10 good sleepers. Next, the researchers placed electrodes and an accelerometer on the dominant thumb of each participant to measure the speed and direction of the thumb’s movements. Then, the researchers made use of transcranial magnetic stimulation (TMS), a Food and Drug Administration-approved treatment for some cases of depression. TMS is able to painlessly deliver electromagnetic currents to precise locations of the brain — non-invasively — and thereby safely disrupt brain activity in these areas.
For this experiment, then, each participant received exactly 65 electrical pulses of TMS to stimulate a specific area of their motor cortex while the researchers watched for involuntary thumb movements. Next, the team of researchers trained each participant for 30 minutes, teaching them to move their thumb in the opposite direction of their involuntary movement. When the training session was completed, the team stimulated participants’ brains with TMS once again. This was their way of measuring the adaptability of participants’ motor cortex — the extent to which their brains could learn to involuntarily move the thumb in a new direction would indicate the level of brain adaptability. “This form of neuroplasticity, following training, is thought to represent the initial steps of encoding simple motor memories,” the researchers wrote in their research paper published in Sleep.
What Did the Team Discover?
The motor cortex region of the brain in those with chronic insomnia was more adaptable to change — more plastic — than in the group of good sleepers. The researchers also found the group of participants suffering chronic insomnia showed more "excitability" among neurons in that very same brain region, suggesting they may be in a constant state of heightened information processing. Their findings, then, were the opposite of what they originally expected.
“We know sleep is important for all types of memory,” Salas said. “So that’s why we had initially hypothesized that people with insomnia might have less plastic or adaptable brains. We were surprised by the results.” Although the increased plasticity was shown only in the motor cortex, the researchers theorize that increased plasticity may be found throughout the brain.
“Other studies have found patients with chronic insomnia do have problems with more complicated tasks, but with simple tasks they seem to compensate,” Salas told Medical Daily. “Maybe this is some kind of evolutionary compensation — we don’t know. But this research is important because it suggests a new target for new treatments.”
Source: Salas RE, Galea JM, Gamaldo AA, et al. Increased Use-Dependent Plasticity in Chronic Insomnia. Sleep. 2014.