Three recent studies have found various ways that chronic insomnia alters brain function and structure. Sleep researchers have known for decades that learning and memory are strongly connected to sleep. These new studies help explain the specific neurobiology behind poor sleep quality and impaired brain functioning.
Humans have evolved to spend one-third of our lifetime asleep. Adults should aim to sleep around 8 hours a night which adds up to roughly 122 days per year of sleep. Your body and mind will function optimally on a two-to-one ratio of wake-to-sleep.
Ideally, by the time you are sixty you will have spent about 20 years of your life asleep, and about 5 years of that dreaming in a state of REM (Rapid Eye Movement) sleep. Unfortunately, the American Academy of Sleep Medicine reports that about 10 to 15 percent of adults have an insomnia disorder that leads to physical and psychological daytime impairment.
Insomnia Creates Hyperactive Brain Plasticity
A Feb. 28 study from Johns Hopkins titled “Increased Use-Dependent Plasticity in Chronic Insomnia” found more "excitability" of neurons in a similar brain region among participants with chronic insomnia. The evidence confirms the notion that some insomniacs are in a constant state of heightened information processing that may interfere with sleep.
"Insomnia is not a nighttime disorder," says study leader Rachel E. Salas, M.D., an assistant professor of neurology at the Johns Hopkins University School of Medicine. "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." Salas and her team published their findings in the March 2014 issue of the journal Sleep.
A lack of sleep during the night has long been linked to decreased memory and concentration during the day. Therefore, Salas and her colleagues suspected that the brains of good sleepers could be more easily retrained... the results, however, were the opposite. The researchers were surprised to find that in some instances the motor cortex in those with chronic insomnia was more adaptable to change—more plastic—than in a group of good sleepers.
The idea was to measure the extent to which participants' brains could learn to move their thumbs involuntarily in the newly trained direction. The more the thumb was able to move in the new direction, the more likely their motor cortexes could be identified as more plastic.
Salas says, “the origins of increased plasticity in insomniacs are unclear, and it is not known whether the increase is the cause of insomnia. It is also unknown whether this increased plasticity is beneficial, the source of the problem or part of a compensatory mechanism to address the consequences of sleep deprivation associated with chronic insomnia.”
Salas concludes, “it is possible that the dysregulation of arousal described in chronic insomnia—increased metabolism, increased cortisol levels, constant worrying—might be linked to increased plasticity in some way. Diagnosing insomnia is solely based on what the patient reports to the provider; there is no objective test. Neither is there a single treatment that works for all people with insomnia. Treatment can be a hit or miss in many patients.”
Insomnia Increases Mind Wandering
An August 2013 study from the University of California, San Diego (UCSD) used brain imaging to help explain why people with insomnia often complain that they struggle to concentrate during the day. The study titled “Neural Correlates of Working Memory Performance in Primary Insomnia” was published in the journal Sleep.
The UCSD researchers found that participants with insomnia did not differ from good sleepers in objective cognitive performance on the working memory task. However, the MRI scans revealed that people with insomnia could not modulate activity in brain regions typically used to perform the task.
"We found that insomnia subjects did not properly turn on brain regions critical to a working memory task and did not turn off 'mind-wandering' brain regions irrelevant to the task," said lead author Sean P.A. Drummond, PhD, associate professor in the department of psychiatry at UCSD. "Based on these results, it is not surprising that someone with insomnia would feel like they are working harder to do the same job as a healthy sleeper."
The research team led by Drummond and co-principal investigator Matthew Walker, PhD, studied 25 people with primary insomnia and 25 good sleepers. Participants had an average age of 32 years. The study subjects underwent a functional magnetic resonance imaging scan while performing a working memory task.
As the task got harder, good sleepers used more resources within the working memory network of the brain, especially the dorsolateral prefrontal cortex. People with insomnia were unable to recruit more resources in these brain regions. Furthermore, as the task got harder, participants with insomnia did not dial down the "default mode" regions of the brain that are normally only active when our minds are wandering.
"The data help us understand that people with insomnia not only have trouble sleeping at night, but their brains are not functioning as efficiently during the day," said Drummond. "Some aspects of insomnia are as much of a daytime problem as a nighttime problem. These daytime problems are associated with organic, measurable abnormalities of brain activity, giving us a biological marker for treatment success."
According to the authors, the study is the largest to examine cerebral activation with functional MRI during cognitive performance in people with primary insomnia, relative to well-matched good sleepers. It also is the first to characterize functional MRI differences in working memory in people with primary insomnia.
Insomnia Reduces Gray Matter in the Frontal Lobes
A February 2014 study of Gulf War veterans from University of California, San Francisco (UCSF) found an association between poor sleep quality and reduced gray matter volume in the brain's frontal lobe, which helps control important processes such as working memory and executive function.
"Previous imaging studies have suggested that sleep disturbances may be associated with structural brain changes in certain regions of the frontal lobe," said lead author Linda Chao, associate adjunct professor in the Departments of Radiology and Biomedical Imaging and Psychiatry at UCSF. "The surprising thing about this study is that it suggests poor sleep quality is associated with reduced gray matter volume throughout the entire frontal lobe and also globally in the brain."
The results show that poorer sleep quality was associated with reduced total cortical and regional frontal lobe gray matter volumes after controlling for potentially confounding variables such as post-traumatic stress disorder, depression, Gulf War Illness, trauma exposure and psychotropic medication use.
"This study emphasizes the importance of seeking medical help if you are troubled by the poor quality of your sleep," said American Academy of Sleep Medicine President Dr. M. Safwan Badr. "A board certified sleep medicine physician can identify the cause of your sleep problem and develop an effective treatment plan for you."
According to the authors, the cross-sectional design of the study did not allow them to determine a causal relationship between sleep and frontal lobe gray matter volume. They noted that additional research is needed to determine if effective treatment of disturbed sleep leads to improved structural and functional integrity of the frontal lobes.
Conclusion: The Performance Triad—Eat, Move, Sleep
Although more research is needed to determine the causal relationship between insomnia and changes in brain structure, it is clear that addressing sleep disturbances should be a top priority. On page 315 of The Athlete’s Way I offer some practical ways to treat insomnia. Sleep and exercise create a perfect circle. Regular exercise helps people sleep better, and high quality sleep helps everyone perform better.
The three components of healthy eating, physical activity and sufficient sleep are cornerstones of a new pilot program called The Performance Triad which was launched by the Office of the Surgeon General and Army Medicine in October of 2013.
The army is advocating a culture shift by encouraging every soldier to develop a mindset that drives them to optimize their health in order to improve their performance and resiliency via the performance triad. Adopting this simple triad can lead to optimal performance, overall well-being, and disease prevention for both soldiers and civilians.
Chronic poor sleep has serious short and long term consequences. Insomnia alters brain function and structure in ways that impair concentration and alertness. Fatigue and drowsiness from poor sleep can lead to slower reflexes and ultimately has the life threatening potential to cause fatal accidents through events like falling asleep at the wheel. Primary insomnia also increases the risk for obesity, cardiovascular disease, and depression.
Lt. Col. Elizabeth Miller at Army Medicine summed up the importance of sleep for soldiers and civilians alike saying: "Success of the sleep health component of the Performance Triad is dependent upon leaders who live and promote healthy sleep—seven to nine hours per day. This will require a culture change. You are not better if you stumble through the day on five hours of sleep—it's not safe."
If you’d like to read more on this topic, check out my Psychology Today blog posts: