Think back to the last time you had trouble sleeping. Remember how you felt lying in bed awake, gazing into a dark room until your clock finally told you to start a new day. Now, imagine having trouble falling asleep or staying asleep every night.
Insomnia is a sleep disorder that affects an estimated 15 percent of the population of the United States. This condition can be a side effect of more serious disorders such as depression or present on its own. To better illuminate this sleep disorder, researchers at the Johns Hopkins University School of Medicine investigated brain activity thought to be linked to insomnia.
Rachel E. Salas, an assistant professor of neurology at the School of Medicine, led the study. Her team analyzed brain function in the motor cortices, which are brain structures associated with planning, control and voluntary movements. They found that the cortices of people suffering from insomnia are more plastic, or adaptable to change, than the cortices of people without insomnia. This suggests that insomniacs’ brains might be more continuously processing information, interfering with sleep.
To carry out the study, the researchers performed transcranial magnetic stimulation (TMS), a procedure that uses a magnetic field to noninvasively stimulate different areas of the brain. Twenty-eight participants were involved in the study: 18 with insomnia and 10 without.
The researchers connected electrodes from the participants’ thumbs to an accelerometer, which allowed them to measure the direction and speed of their thumbs. The participants then received 65 pulses of TMS on their motor cortices. Such stimulation made their thumbs move involuntarily. Following the TMS procedure, the participants worked on moving their thumbs in the 30 minutes of movement, TMS was applied to the motor cortices for a second time. The research design intended to measure the ease with which the participants could retrain their motor cortices. The results indicated that insomniac brains were more easily retained and thus were more plastic than the brains of non-insomniacs. According to Salas, the implications of this research are still unclear. Moreover, researchers do not know if the motor cortex is the only area of the brain affected by insomnia.
Salas highlighted research limitations due to funding shortages: “Funding was definitely one of our limitations to bring more subjects in,” she said. “Honestly, a lot of the studies that are out there using TMS haven’t required large sample sizes. I maintained the same sample size that other studies have used. We would have loved to bring in more volunteers.”
When asked if she would like to continue studying insomnia, Salas answered, “I would love to. The biggest frustration we face is that even though these are common disorders and reduce quality of life, there are still these other more devastating disorders out there. As a result, there isn’t a lot of attention paid and funding for sleep disorders.”
The study will be published in the March edition of the journal Sleep. It was supported by the National Institutes of Health’s National Institute of Child Health and Human Development as well as the National Institute of Arthritis and Musculoskeletal and Skin Diseases.
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