Sleep disorders and mental health: Understanding the cognitive connection

Abstract

Sleep disorders, particularly insomnia, have emerged as a critical public health challenge, with the situation worsened by the coronavirus disease-2019 pandemic. Insomnia symptoms, which affected up to 45% of the population during this period, highlight the urgent need to understand the mechanisms linking sleep disturbances to mental health outcomes. Recent findings suggest that cognitive failures, such as memory lapses and attentional deficits, mediate the relationship between insomnia and emotional disorders such as anxiety and depression. The role of personality traits, particularly neuroticism, adds further complexity, as it may either exacerbate or buffer these effects under specific conditions. This review explores the study by Li et al, which offers valuable insights into the cognitive-emotional pathways influenced by sleep disturbances. The study makes significant contributions by identifying key cognitive mechanisms and proposing the dual role of neuroticism in shaping emotional outcomes. To advance these findings, this letter advocates for future longitudinal research and the integration of targeted interventions, such as cognitive-behavioral therapy for insomnia, into public health frameworks. By addressing insomnia-induced cognitive dysfunction, these strategies can enhance emotional regulation and foster resilience, particularly in vulnerable populations facing the mental health impacts of the pandemic.

Key Words: Sleep deprivation; Emotional dysregulation; Psychological resilience; Personality traits; Cognitive dysfunction; Stress management; Mental wellness; Sleep health promotion; Public health strategies

Core Tip: Sleep disorders such as insomnia significantly affect mental health by contributing to anxiety and depression through cognitive failures. Personality traits such as neuroticism, which is traditionally seen as a vulnerability trait, may either exacerbate or mitigate these effects, adding complexity to its role. While Li et al’s study advances the understanding of these pathways, future longitudinal research is needed to confirm causality. Targeted interventions addressing both sleep quality and cognitive function can offer effective strategies for enhancing emotional resilience in vulnerable populations, particularly amid the mental health challenges of the coronavirus disease-2019 pandemic.

TO THE EDITOR

Sleep disorders, especially insomnia, have emerged as a critical public health concern, and their prevalence was markedly increased by the coronavirus disease 2019 (COVID-19) pandemic. Recent studies have indicated that sleep disturbances affect between 2.3% and 76.6% of the population globally[1], with insomnia symptoms alone accounting for 20%-45% of cases during the pandemic[2]. Factors contributing to sleep disturbances include stress, anxiety, altered daily routines, social isolation, and reduced daylight exposure[3]. The pandemic exacerbated these challenges, particularly among healthcare workers and the general public, increasing the rates of anxiety, depression, and substance use disorders[2,4].

Sleep plays a crucial role in mental and physical health, making it essential for coping with the challenges faced during the pandemic[3]. However, sleep disturbances have profound implications for cognitive functioning, including memory lapse, diminished attention span, and impaired executive function. These cognitive failures not only disrupt daily life but also act as mediators between insomnia and emotional disorders, highlighting the complex interplay between cognitive health and emotional well-being.

Emerging evidence highlights neuroticism, a personality trait characterized by emotional instability, as a moderator in shaping the impact of insomnia-driven cognitive impairments on mental health[5,6]. Interestingly, neuroticism, often regarded as a vulnerability, may act as a protective buffer under specific conditions. This dual role highlights its complexity, which could be summarized to focus on insights for future strategies addressing mental health issues. For instance, future interventions could explore how to leverage the potential protective effects of neuroticism in enhancing emotional resilience, especially for individuals with high neuroticism.

As the prevalence of mental health challenges rises globally, understanding the cognitive mechanisms linking sleep disturbances to anxiety and depression becomes increasingly essential. This review aims to explore how insomnia-related cognitive failure contributes to emotional disorders and advocates for targeted interventions that enhance cognitive function and emotional regulation. Addressing these issues could improve public mental health resilience, particularly in the face of ongoing global stressors.

Critical appraisal of the study

The recent research by Li et al[7], published in the World Journal of Psychiatry, examines a crucial aspect of mental health, offering valuable insights into the mechanisms underlying the relationship between sleep disorders and emotional well-being. Focusing on the role of cognitive failures as a mediator and neuroticism as a moderator in this relationship, the study provides a nuanced understanding of the pathways connecting insomnia with anxiety and depression. This appraisal critically evaluates the design, methodology, and findings of the study, as well as the interpretation of its results.

Study design and methods: The study adopts a cross-sectional design, which is appropriate for exploring associations between variables. The study recruited 1011 adult participants via an online platform using convenience sampling, a pragmatic approach given the constraints of large-scale data collection during the post-pandemic period. The authors employed validated and widely recognized tools such as the Insomnia Severity Index, Generalized Anxiety Disorder-7, Patient Health Questionnaire-9, and the Cognitive Failures Questionnaire. These instruments ensured reliable measurement of key variables such as insomnia, anxiety, depression, and cognitive failures, while the neuroticism subscale of the Chinese Big Five Personality Inventory Brief Version provided a robust framework for assessing personality traits.

Key findings and their implications: The findings revealed a high prevalence of mental health challenges: 41.3% of participants reported anxiety, 44.6% experienced depression, and 36.3% suffered from insomnia. These prevalence rates align closely with the existing literature, particularly involving populations affected by the stressors of the COVID-19 pandemic. Healthcare workers, especially nurses, showed a higher prevalence of these conditions compared to the general population[8,9]. The study establishes cognitive failures as a mediating factor in the relationship between insomnia and emotional health outcomes, demonstrating that sleep disturbances exacerbate cognitive lapses, which, in turn, worsen anxiety and depressive symptoms. Additionally, the authors observed that individuals with lower levels of neuroticism experienced a stronger predictive effect of insomnia on cognitive failures, suggesting that neuroticism may act as a buffer in specific contexts. This finding challenges the conventional view of neuroticism purely as a risk factor, opening avenues for further exploration into its dual role as a potential protective mechanism under certain conditions. However, the study could have further explored the practical implications of this observation, particularly for tailoring interventions for individuals with varying personality traits.

Strengths of the study

The study by Li et al[7] demonstrates a sophisticated approach by integrating cognitive failures as mediators and neuroticism as a moderator in examining the relationship between insomnia and mental health outcomes. This multi-dimensional framework provides valuable insights into the mechanisms linking sleep disturbances to anxiety and depression, expanding on traditional linear models.

The use of validated measurement tools, such as the Insomnia Severity Index, Generalized Anxiety Disorder-7, Patient Health Questionnaire-9, and Cognitive Failures Questionnaire, enhances the reliability of the findings. These tools have well-established psychometric properties, with Cronbach’s alpha values ranging from 0.82 to 0.95, ensuring consistency in the collected data. Additionally, inclusion of the neuroticism subscale from the Chinese Big Five Personality Inventory Brief Version provides a robust framework for assessing personality traits and their influence on mental health.

With a sample size of 1011 participants, the study achieved a high degree of statistical power, allowing for a detailed exploration of associations across demographic subgroups. This is complemented by the application of structural equation modeling and moderated mediation analysis, enabling a nuanced examination of direct, indirect, and moderated effects. The methodological rigor ensures that the statistical results are both robust and insightful.

The focus of the study on post-pandemic mental health makes it highly relevant, especially in light of the persistent challenges posed by the COVID-19 pandemic. This research underscores the need for continued attention to mental health in vulnerable populations by highlighting the prevalence of anxiety, depression, and insomnia. Furthermore, the discussion of neuroticism as a potential protective factor under certain conditions challenges conventional perspectives, offering new directions for research on personality traits and mental health.

Limitations of the study

The cross-sectional study design represents a significant limitation as it prevents the establishment of causal relationships. While the authors successfully demonstrated associations between insomnia, cognitive failures, and mental health outcomes, the temporal dynamics of these relationships remained unclear. For instance, anxiety and depression might contribute to sleep disturbances, creating a bidirectional relationship that cannot be fully captured in this design. Thus, longitudinal research would be necessary to clarify these causal pathways.

Reliance on self-reported data introduces potential biases, such as social desirability and subjective interpretation. Participants may underreport or overreport symptoms based on their personal perceptions or cultural factors, which could skew the results. While using validated tools mitigates this issue to some extent, the inherent limitations of self-report methods cannot be entirely eliminated.

Although this study employed self-reported measures owing to their feasibility in large-scale data collection, future research could benefit from integrating objective methodologies such as polysomnography or actigraphy. Polysomnography measures various physiological parameters, including wake time, sleep time, and sleep architecture. Furthermore, actigraphy is a convenient and cost-effective method that uses a wrist-worn device to track movement patterns to infer sleep-wake cycles[10]. Additionally, neuroimaging techniques such as functional magnetic resonance imaging and electroencephalography-based studies could provide further insights into the neurobiological mechanisms underlying the relationship between sleep disturbances, cognitive failures, and emotional distress.

Another important factor potentially influencing the relationship between sleep disturbances and emotional distress is social isolation. Recent evidence has suggested that social isolation exacerbates both sleep disturbances and emotional dysregulation by limiting social support and increasing perceived stress. Therefore, future studies could adopt a multifactorial mediation model to investigate the combined roles of cognitive failures and social isolation in mediating the association between sleep disturbances and emotional disorders.

The recruitment method, which relied on an online survey platform, poses challenges to the generalizability of the findings. Individuals without access to digital resources or those less inclined to participate in online studies may be underrepresented, particularly older adults or those from lower socioeconomic backgrounds. This limitation reduces the generalizability of the findings.

Although the study identified neuroticism as a moderating factor, its discussion of the practical implications is limited. Although the authors’ observation that neuroticism may act as a buffer in some cases is intriguing, they did not explore how this insight could be translated into actionable interventions. Similarly, while the authors recommended enhancing cognitive function to improve mental health, they did not provide specific strategies or examples of interventions that could achieve this goal.

The study also identified significant demographic patterns, such as higher rates of anxiety, depression, and insomnia among children and younger adults. However, the discussion does not fully explore the underlying mechanisms driving these differences. For example, only children may face unique psychosocial pressures, while younger adults might experience heightened stress due to career or academic challenges during the pandemic. These observations are mentioned but not examined in detail.

Lastly, the absence of neurobiological measures, such as neuroimaging or electrophysiology, limits the ability of the study to explore the neural mechanisms underlying the observed relationships. Integrating such methods in future research could provide a more comprehensive understanding of the connections between sleep, cognitive failures, and mental health.

Comparison with existing literature

Relationship between insomnia, anxiety, and depression: Li et al’s study[7] aligns with recent research on the interplay between sleep disturbances, emotional health, cognitive failures, and personality traits. Multiple studies confirmed the association of insomnia with increased anxiety and depression. For instance, Akram et al[11] found that insomnia exacerbates emotional distress via disrupted regulation and cognitive impairment, while Riemann et al[12] emphasized the bidirectional relationship between insomnia and depression. These findings reinforce Li et al’s conclusion[7], which states that addressing sleep disturbances is critical for improving mental health outcomes.

Role of cognitive failures: Cognitive failures, such as memory lapses and attention deficits, were widely identified as mediators in the relationship between insomnia and emotional distress. Wilkerson et al[13] investigated how insomnia affects daily cognitive performance, demonstrating that cognitive failures often escalate feelings of anxiety and depression by undermining individuals’ coping mechanisms. The study by Wilkerson et al[13] complements the current research by reinforcing the need to address cognitive dysfunctions in sleep-deprived individuals.

Neuroticism as a moderator: Li et al’s study[7] exploration of neuroticism as a moderating factor is supported by several recent investigations. For instance, Schenk et al[14] examined the role of neuroticism in predicting mental health outcomes, finding that high levels of neuroticism increase susceptibility to anxiety and depression in individuals with sleep disturbances. Interestingly, Amestoy et al[15] identified neuroticism as a dual-factor trait that can sometimes buffer against stress by fostering heightened awareness of emotional states, which aligns with Li et al’s nuanced findings on the dual role of neuroticism[7].

Interaction between sleep and emotional regulation: Vassend et al[16] highlighted the interaction between insomnia and emotional regulation, observing that individuals with disrupted sleep often experience heightened negative affect due to impaired cognitive processing. This finding resonates with Li et al’s study[7], which underscores the mediating role of cognitive failures in linking insomnia to emotional dysregulation.

Demographic insights: Li et al’s study[7] also identifies significant differences in mental health outcomes among demographic groups, such as higher rates of anxiety and depression among only children. Iwasa et al[17] similarly observed that familial dynamics and social support influence the severity of emotional distress in individuals with insomnia. Hence, addressing demographic and psychosocial variables is crucial for designing targeted mental health interventions.

Methodological contributions: In terms of methodological rigor, Li et al’s study[7] is notable for its use of moderated mediation models, which allow for a more nuanced understanding of the interaction between cognitive and personality factors. This approach is consistent with that of Harvey et al[18], who employed advanced statistical models to explore the relationship between neuroticism and sleep quality.

Practical implications: The practical implications of Li et al's study[7] align closely with those highlighted in the broader literature. Cognitive-behavioral therapy (CBT) for insomnia (CBT-I) has been widely recommended as an effective intervention for addressing both insomnia-associated cognitive dysfunction and emotional dysregulation. Similarly, Yuksel et al[19] emphasized the importance of tailoring interventions to account for individual differences in personality traits, such as neuroticism, further supporting the need for personalized approaches to improve sleep and emotional well-being.

Comparative unique value: While the findings of Li et al’s study[7] are largely consistent with the existing literature, its unique contribution lies in its detailed analysis of the moderating role of neuroticism. Few studies have explored, to a comparable extent, how personality traits influence the interaction between sleep and mental health. For instance, Akram et al[11] discussed the relationship between neuroticism and insomnia severity but did not explore its moderating effects in depth, highlighting a gap that Li et al’s study[7] effectively addresses.

Clinical implications and future directions

Clinical implications: The study highlights the complex interplay between insomnia, cognitive failures, anxiety, and depression, with neuroticism serving as a moderating factor. These insights offer several significant clinical implications for mental health interventions. First, the identification of cognitive failures as a mediating factor suggests that addressing cognitive dysfunction could be an effective strategy for alleviating the emotional burden of insomnia. CBT, which showed efficacy in treating both insomnia and emotional disorders, could be adapted to target specific cognitive lapses, such as attentional deficits or memory failures, which exacerbate mental health challenges.

The study also underscores the importance of personalized interventions tailored to individual differences in personality traits, such as neuroticism. For individuals with high neuroticism, clinical interventions could include tailored CBT modules focusing on enhancing emotional regulation and resilience. These modules could incorporate strategies such as mindfulness-based cognitive therapy to address increased emotional sensitivity and stress reactivity, which are common in individuals with high neuroticism. Additionally, psychoeducation could help these individuals reframe their emotional responses and develop effective coping mechanisms.

Another critical implication is the need for targeted approaches for demographic groups at higher risk, such as young adults and children, who experience elevated levels of anxiety and depression. These populations may benefit from psychoeducational programs fostering social support and improving coping mechanisms. Mental health practitioners should also be vigilant about the impact of societal factors, such as post-pandemic stressors, which may exacerbate sleep-related and emotional disturbances.

Future directions: Future research should build on the findings of this study by addressing its limitations and expanding its scope. Longitudinal studies are essential to establish causal pathways between insomnia, cognitive failures, and emotional disorders. Furthermore, understanding these relationships over time would strengthen evidence for targeted interventions. Additionally, incorporating neurobiological measures, such as neuroimaging or electrophysiological assessments, could provide insights into the neural mechanisms underlying cognitive dysfunction in sleep-deprived individuals.

Further investigation into the dual role of neuroticism as both a risk factor and a potential buffer against stress-related cognitive failures could guide personalized interventions for different personality profiles. Furthermore, research should explore how cultural and environmental factors influence the relationships between insomnia, cognition, and emotional health.

Interventional studies are needed to test combined approaches, such as CBT for insomnia with cognitive training or emotional regulation strategies, to validate the practical implications of the findings. Additionally, demographic variables such as age, gender, and family structure should be examined to understand their interaction with sleep and emotional disorders. For example, exploration of the unique psychosocial stressors faced by children or young adults could help refine preventive measures.

Demographic factors such as age and family structure may significantly influence the prevalence of sleep disturbances, anxiety, and depression. Younger adults, particularly those facing career instability and academic pressure, are more vulnerable to stress-induced sleep disturbances. Similarly, children and adolescents experience sleep difficulties owing to increased screen time exposure and irregular sleep schedules. Hence, future research should adopt age-stratified analyses to better understand how these vulnerabilities manifest across different age groups and design tailored interventions accordingly.

Emerging evidence suggests that the relationship between sleep disturbances and emotional distress is mediated by neurobiological mechanisms. Disrupted sleep architecture affects prefrontal cortex activity, impairing cognitive control and emotional regulation. Furthermore, alterations in the hypothalamic-pituitary-adrenal axis and increased cortisol levels are linked to increased anxiety and depression symptoms. Thus, incorporating neuroimaging techniques such as functional magnetic resonance imaging and electrophysiological assessments in future studies could provide more comprehensive insights into these underlying mechanisms.

Finally, addressing the public health implications of this research requires collaboration between researchers, clinicians, and policymakers. Community-based initiatives, such as workplace wellness programs and school-based interventions, could reduce insomnia and its mental health impacts. Public health campaigns should focus on integrating sleep education into workplace programs, offering workshops on stress management and sleep hygiene, especially for highly stressful roles. Similarly, school programs can educate students on the importance of sleep for cognitive and emotional health, potentially lowering long-term mental health risks.

CONCLUSION

The study highlights the complex interplay between insomnia, cognitive failures, anxiety, and depression, with neuroticism serving as a moderating factor. Insomnia not only disrupts sleep patterns but also impairs cognitive functions, worsening anxiety and depression. Furthermore, the moderating role of neuroticism emphasizes the need for personalized interventions considering individual personality traits. The findings have significant implications for clinical practice, urging the integration of targeted therapies such as CBT-I, mindfulness, and emotion-focused approaches to address cognitive and emotional dysregulation. Further research, including longitudinal, interventional, and neurobiological studies, is needed to refine therapeutic strategies. Additionally, public health initiatives promoting sleep hygiene and emotional well-being at the community level could help address these challenges on a broader scale. As the global burden of mental health issues continues to increase, particularly after the pandemic, research into the interplay between sleep and emotional health is critical. We can develop more effective interventions that enhance resilience, improve quality of life, and reduce the societal costs of mental health disorders by addressing these interconnected pathways.