Sleep Deprivation Effects on Brain and Cognitive Function

Introduction: Neurocognitive Consequences of Sleep Deprivation

Studies on sleep deprivation consistently display negative effects on mood, cognitive behaviour, and motor function as a result of a rising propensity for sleep as well as the destabilization of the waking state. Unique neurocognitive domains such as executive attention, working memory, and higher cognitive behaviours are particularly susceptible to sleep loss. In human beings, functional neurophysiological and metabolic studies demonstrate that neural systems involved in executive function—most notably the prefrontal cortex—are more prone to sleep deprivation in certain individuals than in others. Recent chronic sleep deprivation studies, which closely replicate the kind of sleep loss experienced in everyday life, show that deep neurocognitive deficits accumulate over time even as individuals subjectively adjust to their reduced sleep. All sleep deprivation related to disease-associated conditions such as restless legs syndrome and sleep apnea equally leads to neurocognitive function reductions similar to those shown in sleep restriction studies. Functional deficits related to sleep disorders are most often viewed as a function of disease severity; nevertheless, recent experiments suggest that individual vulnerability to sleep loss may play a more vital role than previously believed (Durmer & Dinges, 2005).

Sleep deprivation is closely linked to considerable financial, social, and health-related costs, largely because it impairs cognitive behaviour through rising sleep instability and disrupted neurobehavioural performance. Cognitive performances most affected by sleep loss include psychomotor and cognitive speed, executive and vigilant attention, higher cognitive functions, and working memory. Chronic sleep-restriction studies—which assess the type of sleep deprivation individuals experience due to premature sleep reduction and sleep fragmentation caused by lifestyle and disorder—show that cognitive deficits accumulate to severe levels over time, with the affected individual often unaware of the deterioration. Functional neuroimaging has demonstrated that the prolonged cognitive lapses characteristic of sleep deprivation involve distributed changes in brain regions including parietal and frontal control areas and thalamic and secondary sensory processing areas. There are substantial individual differences in cognitive susceptibility to sleep deprivation, potentially rooted in genetic traits associated with the regulation of circadian rhythms and homeostatic sleep drive (Goel, Rao, Durmer & Dinges, 2009).

The Impact of Chronic Sleepiness

People suffering from sleep deprivation often describe feeling mentally foggy. Research identifies three primary reasons why this occurs.

1. Sleepiness slows thought processes. According to scientists who study sleepiness, sleep deprivation leads to reduced concentration and alertness. Paying attention and maintaining focus becomes difficult, meaning a person can become confused more easily. This hinders the ability to carry out tasks requiring complex thought or logical reasoning. Judgement is also impaired by sleepiness, as individuals struggle to adequately assess situations and choose appropriate courses of action (Peri, n.d.).

2. Sleepiness impairs memory. Research indicates that the neural connections responsible for human memories are strengthened during sleep. Sleep embeds what people have learned and experienced during the day into short-term memory, and every sleep phase appears to play a unique role in consolidating new ideas and information. When sleep is disrupted or cut short, these cycles are interfered with. A sleep-deprived person may frequently forget or misplace important things, and the inability to concentrate compounds the memory impairment further (Peri, n.d.).

3. Poor sleeping habits make learning more difficult. Sleep deprivation hinders the ability to learn in two distinct ways. Because an individual cannot pay adequate attention when sleepy, acquiring new information becomes harder, making effective learning more difficult. Memory—a vital tool for learning—is also compromised. Sleepiness in children often leads to hyperactivity, further hindering learning, while adolescents may lose diligence, focus, and the memory capacity needed to perform well academically (Peri, n.d.).

References

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