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Sleep is important, it’s a simple fact. It has long been proven that memory and learning are connected to sleep. Some of us learned this the hard way as we struggled through high school and college, when there never seemed to be enough time to sleep. And without enough sleep, many of us also found that we had a harder time remembering things.
Study after study has expanded and reinforced our understanding of the connection between a good night’s sleep and cognitive functioning. As studies have continued, however, there has been even more evidence to suggest a relationship between chronic insomnia and long-term effects on the brain. So, how does chronic insomnia affect the brain?
What is Insomnia?
Insomnia is a disorder that causes difficulty falling asleep (onset) or staying asleep (maintenance). It can be acute or chronic, but generally occurs at least three times a week for one month. This disorder is widespread, and The National Institute for Health states that 10% of adults worldwide struggle with insomnia. While science has had trouble pinpointing a direct cause for insomnia, studies are beginning to show the long term physical effects of it on the human brain.
Chronic Insomnia Doesn’t Just Affect You at Night
The first thing you have to understand about how insomnia affects your body is that insomnia doesn’t just affect you at night when you’re trying to sleep. A
Johns Hopkins study, “Increased Use-Dependent Plasticity in Chronic Insomnia”, proved that the neurons in the brains of people with insomnia showed more “excitability.”
Scientifically, excitability can be defined as the propensity of the neuron to generate an output signal from a given input signal. In layman’s terms, this study essentially showed that neurons in brains of people with insomnia are more prone to be “active.” Study leader Rachel Salas, M.D., an assistant professor of neurology at Johns Hopkins, put it this way: “Insomnia is not a nighttime disorder. It’s a 24-hour brain condition, like a light switch that is always on.” All of this neural activity has long-lasting effects on a person’s body.
Chronic Insomnia’s Effect on Memory
A recent study at the University of California at San Diego (UCSD) sought to highlight the effects of chronic insomnia on “working task memory.” Working task memory is your brain’s ability to process and store short-term information which can be referred to in order to complete a task. The study showed that people with insomnia do not differ from good sleepers in objective cognitive performance; however, people with insomnia have trouble regulating activity in areas of their brain usually activated to perform the task.
During the study, participants completed a working memory task (remembering a series of numbers) while having their brains scanned by a functional MRI. The brains of people with insomnia showed less activity in areas involving working task memory. As the tasks increased in difficulty, participants without insomnia showed activity in the region of their brain called the dorsolateral prefrontal cortex, an area involved in working task memory.
The brains of people with insomnia, however, showed no changes in the same area. Additionally, participants without insomnia turned off parts of their brain involved in “default mode” as the tasks got harder, whereas those with insomnia did not. “Default mode” brain regions are active when you aren’t focused on anything; they are also known as the “mind-wandering” areas of your brain.
The study was able to show that the areas of the participants’ brains that weren’t working properly were due to sleep deprivation. Essentially, the fact that these people were unable to sleep had changed their brain’s ability to do its job. This research may explain why insomniacs struggle to concentrate or complete tasks.
Chronic Insomnia Affects Cognitive Functions
Another study at the University of California at San Francisco (UCSF) found an association between poor sleep quality and reduced gray matter in the frontal lobe of Gulf War veterans. Gulf War veterans who were suffering from insomnia were shown to have reduced gray matter in their frontal lobes
The frontal lobe helps control important neurological processes such as working task memory and executive function. The UCSF study showed that poorer sleep quality, such as sleep quality among patients with chronic insomnia, is associated with total cortical and regional frontal lobe matter volumes, which causes cognitive deficits in attention, executive function, and nonverbal memory.
Cognitive deficits are impairments in mental processes that allow your brain to take in information and knowledge. Cognitive deficits also affect neurological processes that drive how you understand and act in the world.
Executive functions are a set of neurological processes that involve managing yourself and your resources in order to complete a task or reach a goal. Neurologists have defined those processes as inhibition, shift (the ability to generate solutions when you encounter an unforeseen problem), emotional control, initiation, working memory, planning/organization, organization of materials, and self-monitoring.
Nonverbal memory is our brain’s ability to take in, store, and recover information about shapes, faces, images, songs, smells, tastes, sounds, and feelings. Nonverbal memory makes it possible to retain and remember content without language.
Higher Risk for Cardiometabolic and Neurocognitive Disorders
The National Institute of Health published a study by two Penn State sleep researchers who were able to show that people who suffer from insomnia are at a higher risk for cardiometabolic and neurocognitive disorders due to long-term poor sleep quality.
Cardiometabolic disorders are metabolic or cardiovascular diseases such as hypertension and diabetes. The study showed that patients with insomnia often had a higher nighttime systolic blood pressure, reduced day-to-night systolic blood pressure dipping, impaired heart rate variability, lower cardiac pre-ejection period, and poorer indices of glucose metabolism. All of these symptoms can lead to cardiometabolic diseases, which collectively are the leading cause of death worldwide.
Patients with insomnia in this study also demonstrated poorer neuropsychological performance on tests of processing speed, switching attention, and a number of short-term visual memory errors. All of this was also shown to be a result of the long-term poor sleep quality found in those suffering from chronic insomnia.
Working to Reduce Chronic Insomnia’s Effects on the Brain
It’s no question that lack of sleep has a significant impact on your brain and its functioning. Memory, focus, and mood are all impacted by sleep deprivation. From neuronal excitability to working task memory and executive function to cardiometabolic disorders, research is beginning to show the long-term effects of insomnia on the brain. So what can you do to combat this?
Sleep experts suggest developing consistent routines around sleep. You can also improve your sleep by creating a healthy sleep environment — keep your bedroom free of electronics, dim the lights, and keep your room at a comfortable temperature. In doing so, you can minimize the risk of developing “sleep debt,” a continual lack of sleep driven by irregular sleep routines.
Experts also recommend a minimum of seven hours of sleep per night because sleep debt cannot be repaid with weekend payments!