The brains of people with insomnia may have more plasticity than those of people who sleep well, new research suggests.
The motor cortex, which is the part of the brain that controls movement, tends to be more flexible and active in insomniacs than in people who don't have trouble sleeping, according to a new study.
"Insomnia is not just a nighttime disorder; it's a 24/7 disorder," said study author Rachel Salas, an assistant professor of neurology at the Johns Hopkins University School of Medicine. People with insomnia may struggle with increased cortisol levels and anxiety on a daily basis, Salas said.
The findings could give researchers a better understanding of the causes of insomnia, or the effects of the condition, the researchers said.
In the study, the researchers used a method called transcranial magnetic stimulation (TMS) to trigger areas of the motor cortex in 28 adult participants, 18 of whom were insomniacs and 10 of whom didn't have trouble sleeping. The brain stimulation caused the participants to move their thumbs in a certain direction, involuntarily.
The researchers used accelerometers placed on the participants' thumbs to measure their movements, and then looked at how easily participants could learn to move their thumbs in the opposite direction of the involuntary movement. The more easily a person was able to move his or her thumbs in the opposite direction, the more flexible the person's motor cortex was likely to be, the researchers said.
Although the researchers had suspected that the brains of the insomniacs would be less rested — and, therefore, harder to retrain — they found the opposite: Chronic insomniacs retrained more easily, because their brains exhibited more plasticity.
"It is hard to say whether it is a good thing or not," she said, referring to the insomniac brains' capacity for increased plasticity. It is possible that there may be an association between the increased plasticity and "dysregulation of arousal" characteristics of insomnia, such as increased metabolism, cortisol levels and anxiety, Salas said.
It's not clear, either, whether or how the increased plasticity contributes to the symptoms of insomnia, or whether it is insomnia that causes increased plasticity in the first place.
"It is a chicken-or-the-egg question," Salas said.
The results suggest that TMS could one day be used to treat insomnia, similar to the way it's used to treat people with depression, she said.
The study is published in the March issue of the journal Sleep.