Neuropsychological Implications of Insomnia

By Ivy Wong

As students, we are no strangers to late nights. Whether it’ s homework, revision, nighttime socializing, or revenge bedtime procrastination, we frequently find ourselves staying up when we should most definitely be asleep. While we may keep ourselves up for various reasons, some people simply cannot fall asleep, however much they want to — insomniacs.

Insomnia: Persistent difficulty with sleep initiation, duration, consolidation or quality

According to the American Academy of Sleep Medicine ’ s ICSD-3 manual, “insomnia ” is defined as “ persistent difficulty with sleep initiation, duration, consolidation or quality. ” , and is used to describe the presence of polysomnographic evidence of disturbed sleep. The condition ’ s prevalence in teens is as high as 23.8%, and as high as 60% among adults in some parts of the world. Insomnia is said to be caused by a state of hyperarousal, the disorder is frequently attributed to environmental, physiological, or psychological factors, such as stress, anxiety, consumption of certain substances, health problems such as sleep apnea, etc.

In a 2014 study published in the European Journal of Medicine, the R-fMRI results of 15 healthy patients were compared to that of 15 primary insomnia patients, connectivity was weaker between the superior parietal lobe (involved in attention and visuospatial perception) and dorsolateral prefrontal cortex (involved in executive functions including working memory and selective attention). Thus, one can conclude that insomnia leads to a decrease in task performance, backed up by a second study done in 2013 by UCSD. While there is no difference in objective cognitive performance between insomniacs and non-insomniacs, people with insomnia have trouble regulating activity in areas of their brain usually activated to perform the task. In the study, patients with insomnia showed increased activity in the dorsolateral prefrontal cortex, an area involved in working task memory. However, the brains of non-insomniacs showed no such increase in activity.

Furthermore, a 2018 study shows that insomnia decreases gray matter around the dorsolateral prefrontal and middle cingulate cortices, as well as the frontal lobe. Gray matter contains most of the brain ’ s neurons ’ cell bodies, and is heavily involved in decision making, emotion control, muscle control, etc. The frontal lobe controls important cognitive functions in humans, including but not limited to executive function, ability to communicate, problem solving, memory, etc. The reduction of gray matter around the frontal lobe implies a possibility of cognitive deficits in attention, executive function, and nonverbal memory.

While impaired function is commonly attributed to fatigue from the lack of sleep, it can be shown that insomniacs are affected cognitively on more than a psychological level. Thus, one can say that this leads to a more ‘ socially acceptable ’ reason for impaired functioning, as currently most are predisposed to accept a scientific reasoning over an emotional one.

Affecting brain structure, insomnia also impacts daily functioning. The quality of life deteriorates due to the side effects of insomnia, such as fatigue, decreased ability to focus or communicate, decrease in mood, etc. This can lead to diminished functioning in day to day life, as well as affecting one socially, emotionally, and academically. Insomniacs show subclinical levels of depression and anxiety, as well as a possible increase in suicide ideation, and insufficient sleep impacts one ’ s ability to regulate and evaluate emotion. Psychological explanations for the association between poor sleep and negative mood suggest a role for enhanced cortical arousal that leads to ruminations and difficulty sleeping. Neurobiological explanations, by contrast, suggest the dysregulation of the circadian pacemaker in the suprachiasmatic nucleus (SCN) in the hypothalamus, leading to neurobiological dysfunctions with a particular focus in the prefrontal cortex. As these regions (critical for modulating sleep processes, and for the regulation of mood and brain outputs from the amygdala) become unable to perform their roles, a plausible brain-system explanation for the link between poor sleep and negative mood is provided..

The hypothalamus plays a crucial role in our body, such as releasiung hormones and regulating body temperature

Apart from difficulties in mood, insomniacs frequently present with fatigue (which none of us are strangers to). For instance, 20% of car accidents happen with sleepiness as one of the main causes. Furthermore, their schedule is disturbed further as they try to make up for little or non-restorative sleep at night, by sleeping longer in the morning. While they may seem to be present, they are having microsleeps when awake, similar to a drowsy driver, they are less able to focus well, as well as more likely to respond slower to stimulus, and have a decreased ability to function. Their working memory capacity is also affected (as discussed above), and they have difficulty solving problems (e.g. mental arithmetic).

Further implications:

Insomnia is often trivialised in relation to other comorbid conditions such as chronic pain, substance use disorder, cardiovascular disorders, etc. This is possibly due to the toxic culture rising up around work, in which workaholics are praised for neglecting their personal health in favor of their product. Sleep is seen as a ‘luxury ’ , as one can stay awake through willpower, caffeine, and various means. Thus, insomniacs are often seen as hardworking, or even envied for the ability to stay up later and complete more work. With the romanticisation of insomnia, the issue is trivialised, which is particularly concerning amongst teens and students who are still growing and thus need their sleep. However, as current society values work over personal health, competitive culture amongst colleagues or classmates often rises up around sleep (or lack thereof). However, taking into account its impact on cognitive function and emotional regulation, perhaps it should be taken higher into account. Abnormal cognitive profiles may be thought to be due to a psychological cause, when it is in fact caused by poor sleep. Alternatively, the impact of a co-morbid problem may be overestimated, and irregular performance may be attributed to poor motivation, poor effort, or anxiety issues.

Sleep problems can also interfere with rehabilitation outcomes. The failure to resolve sleep issues will impact on rehabilitation, as interventions are less likely to be effective, as shown in Castriotta et al., 2009, in which insomnia impacts the degree to which cognitive rehabilitation helps patients who suffered traumatic head injuries.

Sleep problems are also at a risk of causing complications if they remain undiagnosed. Clear links have been shown between sleep problems and increased morbidity and mortality (e.g. increased risk of heart conditions or diabetes). They also have a detrimental effect on neurological disorders by increasing the risk of stroke occurrence and outcomes.

Finally, poor sleep degrades the quality of life of vulnerable populations and may hasten progression of neurological and psychological disorders. The higher prevalence of insomnia in women begins in adolescence, and it is especially high during menopause. Insomnia also has a higher prevalence in the elderly population and individuals with low socioeconomic status or poor baseline health. Furthermore, social or societal stressors are associated with insomnia. For example, studies show that the incidence of insomnia in homeless people was twice that of the general population (41% vs 19%). Insomnia is also well documented in patients of mental illnesses, such as depression, anxiety, PTSD, etc. In childhood disorders (such as ADHD), the lack of diagnosed sleep problems (as many as 1 in 4 remain undiagnosed) may heavily affect the development and severity of their disorders.

Coupling the debilitating effects of insomnia with the stressors and effects present in the lives of vulnerable populations, it can be seen that insomnia can greatly affect the quality of life of vulnerable individuals, piling on the side effects of insomnia on top of their already great suffering.

Treatments:

While your first instinct might be to turn to sleeping pills, studies have shown that sleeping pill users have a high risk of developing dependence and addiction to the medication. Furthermore, it has been postulated that sleeping pills (such as Xanax) are linked to higher chances of developing dementia.

Instead, cognitive behaviour therapy has been suggested as a way of treatment for insomnia (CBT-I). Psychologists employ techniques such as stimulus control therapy (set a consistent time and place for sleep), relaxation training and meditation, remaining passively awake (avoiding any effort to fall asleep, letting go of the worry, and thus relaxing and making it easier to fall asleep), etc. A 2015 review of over 20 different CBT-I trials found that on average, insomniacs who used CBT-I fell asleep faster by 20 minutes and spent 30 fewer minutes awake. The reason why CBT-I is preferred over sleeping pills and other remedies is that it gets to the heart of the issues – the problematic attitudes and behaviors the patient has around sleep. By addressing the underlying reasons of insomnia, CBT can solve the problem at its root.

While insomnia is common and tragically unavoidable for many of us, none of us, not even science, can deny the importance of sleep for day-to-day existence and functioning. So, if you ’ re lucky enough to not have insomnia, go to sleep!

Bibliography

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1978319/ Insomnia: Definition, Prevalence, Etiology, and Consequences, Thomas Roth, 2007

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164454/ Insomnia in Adolescence., Innessa Donskoy and Darius Loghmanee, 2013

https://pubmed.ncbi.nlm.nih.gov/21249453/ Bastien, C. H. (2011). Insomnia: Neurophysiological and NeuropsychologicalApproaches. Neuropsychology Review, 21(1), 22–40. doi:10.1007/s11065-011-9160-3

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5860517/ The Effect of Insomnia on Neuropsychological Functioning in Patients with Comorbid Symptoms of Pain, Fatigue, and Mood Disorders

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https://link.springer.com/article/10.1186/2047-783X-19-32 Functional connectivity changes between parietal and prefrontal cortices in primary insomnia patients: evidence from resting-state fMRI

https://pubmed.ncbi.nlm.nih.gov/29411240/ Li, M., Yan, J., Li, S., Wang, T., Wen, H., Yin, Y., … Jiang, G. (2018). Altered gray matter volume in primary insomnia patients: a DARTEL-VBM study. Brain Imaging and Behavior. doi:10.1007/s11682-018-9844-x

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https://www.ajmc.com/view/insomnia-overview-epidemiology-pathophysiologydiagnosis-and-monitoring-and-nonpharmacologic-therapy