Researchers Identify Brain Differences Linked to Chronic Insomnia

New research published in the March 2014 issue of Sleep has found that chronic insomniacs have more plasticity and activity in the area of the brain that controls movement, which suggests insomnia is a 24-hour brain condition, rather than a nighttime disorder.

For their study, Rachel E. Salas, MD, of the Johns Hopkins University School of Medicine, and her colleagues used painless transcranial magnetic stimulation (TMS) in a group of 28 adult participants — 18 of whom suffered from insomnia for at least 1 year, and 10 of whom were good sleepers.

The study participants wore electrodes on their dominant hand’s thumb, as well as an accelerometer to measure the speed and direction of their thumb movements. Additionally, each subject received 65 TMS pulses, which stimulated areas of the motor cortex while the investigators recorded any involuntary thumb movements linked to the stimulation.

The researchers then trained the patients for 30 minutes, teaching them to move their thumbs in the opposite direction of the original involuntary movement. TMS was reintroduced to find out the extent to which the participants’ brains could learn to move their thumbs involuntarily in the newly trained direction. The more the thumb moved in the new direction, the more likely the subject’s motor cortex was considered to be more plastic.

The investigators expected good sleepers would be retrained more easily, given that a lack of sleep has been linked to decreased memory and concentration during the day. Instead, the researchers found significantly more plasticity in the brains of the chronic insomnia patients.

Thus, the authors concluded the motor cortex of chronic insomnia patients is more adaptable to change than that of good sleepers. They also found more “excitability” among neurons in the same region of the brain for those with chronic insomnia, which provides evidence that insomniacs are in a constant state of heightened information processing that may interfere with sleep.

However, it remains unknown whether the increase in brain plasticity in insomniacs is the cause of insomnia, or if increased plasticity is beneficial, the source of the problem, or part of a compensatory mechanism to cope with sleep deprivation.

Nevertheless, the researchers said their study suggests TMS may play a role in diagnosing insomnia or prove to be a potential treatment for insomnia.