Around 15% of the US population has insomnia - the inability to sleep. Now, researchers have found that people who have chronic insomnia have more activity and plasticity in the area of the brain that controls movement, compared with sound sleepers.

This is according to a study published in the journal Sleep.

To reach their findings, researchers from Johns Hopkins University School of Medicine in Baltimore, MD, assessed 28 participants. Of these, 18 had experienced insomnia for more than 1 year, while 10 were deemed good sleepers.

The subjects were required to wear electrodes on the thumb they used most frequently. Using transcranial magnetic stimulation (TMS), 65 painless electrical pulses were sent to the brain to stimulate the motor cortex. This is the region of the brain that controls all voluntary body movements.

Any involuntary thumb movements from the participants were measured, and an accelerometer was used to measure the speed and direction of these thumb movements.

The investigators then spent 30 minutes training each patient to move their thumb in the opposite direction of their original involuntary thumb movements, before reintroducing the electrical pulses.

The researchers say they wanted to see whether the participants' brains could be effectively trained to move their thumbs involuntarily in the opposite direction.

They explain that the more the thumb was able to move in the newly trained direction, the more activity and plasticity - adaptability to change - there would be in the motor cortex of the subjects' brains.

More activity and plasticity in the motor cortex of chronic insomniacs

The researchers were surprised to find that the brains of the participants who had chronic insomnia could be more easily trained than the brains of good sleepers, meaning they had higher levels of activity and plasticity in the motor cortex region.

Past studies have shown that individuals with chronic insomnia are constantly processing information in the brain and that this disrupts sleep. The investigators say these most recent findings add to this notion.

Lead author Dr. Rachel E. Salas comments:

"Insomnia is not a nighttime disorder. It's a 24-hour brain condition, like a light switch that is always on. Our research adds information about differences in the brain associated with it."

However, Dr. Salas says it is unclear as to whether increased plasticity in the brain's motor cortex is a cause of insomnia or whether it is a part of a "compensatory mechanism" that attempts to combat problems linked to chronic insomnia.

Chronic insomnia can cause increased metabolism, increased cortisol levels and constant worrying. Dr. Salas adds that these factors could be linked to increased plasticity.

Overall, she says these findings show that TMS could play a part in the diagnosis of insomnia and could even be used to treat insomnia by reducing neuronal activity in the motor cortex.

Medical News Today recently reported on a study detailing the discovery of a molecular brain switch that sends us to sleep.