Introduction

Quality of life (QoL) is a crucial factor that determines an individual’s health and well-being1,2. It is inherently subjective, reflecting personal satisfaction with life and a sense of fulfillment or achievement derived from one’s experiences3,4. An improved QoL is typically linked with numerous benefits, including better physical health, enhanced sleep quality, fewer negative emotions, and a more optimistic outlook on life; moreover, better QoL contributes to stronger familial relationships and a more cohesive community. However, the coronavirus disease-2019 (COVID-19) pandemic, on a global scale, has precipitated multifaceted challenges, notably imposing significant psychological burdens on the general population5, and particularly degrading QoL and mental health for many due to its pervasive effects6,7,8,9,10,11,12. This is especially evident in psychological outcomes such as depression, anxiety, and insomnia13. In China, the impact of COVID-19 on mental health has been substantial, with heightened levels of anxiety, depression, and insomnia observed particularly among adolescents14. This general decline in QoL presents a broad context in which specific mental health issues—like post-traumatic stress disorder (PTSD)—can emerge and further exacerbate the situation. PTSD is a chronic mental health issue that can develop following exposure to traumatic or life-threatening events15. Characterized by symptoms such as re-experiencing traumatic events, avoidance of trauma-related stimuli, adverse changes in cognition and mood, and increased arousal, PTSD leads to substantial physical and psychological distress16,17,18. This distress manifests as emotional turmoil, diminished stress resilience, and a pessimistic outlook on the future, severely impacting cognitive functions and problem-solving abilities and disrupting daily activities19,20.

The COVID-19 pandemic, characterized by its unpredictability, extremity, duration, and the threat posed by an unfamiliar and deadly danger, constitutes a potentially traumatic event21. Studies suggest that health crises of pandemic proportions can lead to PTSD symptomatology22,23. Factors associated with PTSD in this context include mental health issues such as depression, anxiety, and insomnia; social isolation; changes in daily routines; direct or indirect exposure to infected individuals; and negative coping mechanisms13,21,24,25,26.

Additionally, adolescents face more abundant biopsychosocial changes and challenges in their daily lives than others and are more prone to PTSD16,18. Research has shown that individuals with PTSD, exacerbated by COVID-19-related stressors, are at an elevated risk of suicidal thoughts, attempts, and deaths27. Sun and colleagues documented approximately 4.6% of the general population experienced PTSD during the COVID-19 pandemic28, while Liang et al. reported nearly 40.4% of adolescents were prone to psychological issues, including 14.4% showing symptoms of PTSD29. These findings highlight the need for increased attention to the mental health of adolescents, especially concerning the impact of COVID-19-related PTSD on their QoL.

Insomnia is widely recognized as a key symptom of PTSD30,31. According to cognitive dissonance theory, traumatic threats can lead individuals to become excessively concerned about their health, thereby intensifying their perception of risk32. This heightened state of concern, typical in individuals with PTSD, often manifests as hypervigilance and increased startle response, both of which can significantly impair sleep quality and consequently diminish overall QoL. Additionally, researchers have identified insomnia as a crucial intermediary factor influencing the relationship between PTSD symptoms and suicidal tendencies33,34. Another study underscored the role of insomnia in mediating the association between PTSD and hypertension35, a condition that can severely impact an individual’s physical and mental well-being, thus leading to a marked decline in QoL.

The chronic nature of such conditions can potentially lead to increased despair and, ultimately, suicidal thoughts. In the context of the COVID-19 pandemic, one study focusing on the general Chinese population reported a significant prevalence of insomnia, with rates reaching 29.2%36. And the factors associated with insomnia related to COVID-19 include female gender, college education, urban residence, presence of comorbidities, taking naps during the daytime37, problematic social media use38,39, COVID-19-related worries, and feelings of loneliness40. Further research has shown that, in the presence of insomnia, the direct effect of problematic social media use on subjective well-being is insignificant39.

Although previous studies have illuminated the influence of insomnia in the interaction between PTSD and QoL from various angles, they have not provided concrete data specifically on the role of insomnia as a mediator in the relationship between COVID-19-related PTSD and QoL in adolescents. To fill this gap in the literature, our study aimed to concentrate on the adolescent demographic within the general population in China and examine the following hypothesis:

Hypothesis 1: Insomnia plays a mediating role in the relationship between COVID-19-related PTSD and QoL among adolescents.

Resilience is defined as an individual’s capacity to maintain or regain mental health in the face of adversity, trauma, or significant stress41. According to the protective factor model of resilience theory, although hazardous factors negatively impact individuals, resilience serves as a moderator, interacting with these risk factors and lessening the severity of their adverse effects42. Individuals with higher levels of resilience are more adaptable in managing unexpected events, thereby reducing their harmful impact. Resilience can be viewed as a defense mechanism that enables people to thrive in the face of adversity, and improving resilience may be an important target for treatment and precaution43,44. The association between bad-state resilience and depressive symptoms was partially mediated by affective temperaments45. A negative mediating effect of psychological resilience was identified between the impact of COVID-19 and PTSD46. Another study demonstrated that resilience acted as a chain mediator in the relationship between fear of COVID-19 and PTSD47. Further investigation into family resilience revealed that family communication served as a mediator in the association between family resilience and family functioning during the COVID-19 pandemic48.

However, resilience scores reportedly declined from 2020 to 2022 during the COVID-19 pandemic49. Researchers have demonstrated the significant moderating roles of resilience between both sleep quality and subjective well-being50 and sleep quality and emotional dysfunction51. Adolescents, having lived through prolonged unusual circumstances during the pandemic, faced numerous psychological stresses, potentially leading to anxiety, depression, and suicidal thoughts. These issues can significantly affect their QoL. Moreover, these negative emotions have, for some, persisted post-pandemic, potentially leading to the development of COVID-19-related PTSD, which can further affect an individual’s QoL. In this complex dynamic, the role of resilience warrants further exploration. Therefore, we also sought to explore the following hypothesis:

Hypothesis 2: Resilience moderates the relationships among COVID-19-related PTSD, insomnia, and QoL in adolescents.

The aim of this study was to examine the impact of COVID-19-related PTSD, insomnia, and resilience on adolescents’ QoL. Specifically, we sought to explore (1) the mediating role of insomnia in the relationship between COVID-19-related PTSD and QoL and (2) the moderating role of resilience within this dynamic (Fig. 1). Furthermore, the purpose of this research was to provide valuable insights that may have practical implications for mitigating the specific mental health consequences of the pandemic, especially PTSD.

Figure 1
figure 1

Associations between COVID-19-related PTSD and adolescent QoL: hypothesis diagram of a moderated mediating model. PTSD post-traumatic stress disorder, QoL quality of life.

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Methods

Participants

We conducted a non-random, cross-sectional study utilizing an online survey to evaluate mental health issues among junior and senior high school students. The survey data were collected from January 8th to January 18th, 2023. To ensure the objectivity and representativeness of the investigation, we selected one province each from eastern, western, northern, southern, and central China. Students from Xinjiang, Shandong, Inner Mongolia, Guangxi, and Hebei provinces participated in the questionnaire survey. We distributed the questionnaires to these schools via the Wenjuanxing platform. The questionnaire began with a standard introduction explaining its purpose and requirements. All participants and their parents consented to the survey, ensuring voluntary participation. The survey was conducted anonymously, and the participants were not compensated for their participation. The inclusion criteria for participants in the study were as follows: (1) being of Chinese nationality; (2) aged between 12 and 18 years; (3) enrolled as junior or senior high school students. A total of 53,064 students were invited to participate in the online survey. To guarantee data quality, we excluded data from 2398 respondents (4.23%) who completed the questionnaire in under 300 s. The final sample comprised 50,666 adolescents aged 12–18 years.

The ethical standards from the 1964 Declaration of Helsinki and its later amendments were followed. This study received approval from the Ethics Committee of Beijing Huilongguan Hospital.

Measures

General Information Questionnaire

The demographic characteristics incorporated into the questionnaire for this study encompassed birth year, residence, gender, current grade level (ranging from grades 7 to 12), history of COVID-19 infection, and the frequency of COVID-19 infections (detailed questionnaire information is provided in the supplementary materials).

Children’s Revised Impact of Event Scale

Developed by Horowitz et al. in 197952, the Children’s Revised Impact of Event Scale (CRIES) is widely used to assess trauma in children. The tool has been refined over time to encompass 13 particular items crafted explicitly for children53, in which “that event” was specifically referred to as “the COVID-19 pandemic.” The scale utilizes a rating system with four response options, scored as 0, 1, 3, or 5, total possible score ranges from 0 to 65. The Chinese version of the CRIES-13 has previously demonstrated good reliability, with a Cronbach's alpha of 0.81, as reported by Jing et al.54. The split-half reliability of the CRIES-13 was found to be 0.85. The Spearman rank-order correlation coefficients between the total score and individual items were 0.83 for the intrusion factor, 0.75 for the avoidance factor, and 0.85 for the hyperarousal factor. In our current study, the scale exhibited satisfactory internal consistency, evidenced by a Cronbach's alpha coefficient of 0.72.

Pittsburgh Sleep Quality Index

The Pittsburgh Sleep Quality Index (PSQI), created in 1989 by Buysse et al. in the United States55, is a subjective measure for assessing sleep quality. It was translated into Chinese by Liu et al. in 199656. Previous studies have demonstrated that the scale has good reliability and validity in the Chinese adolescent and college population57,58. Following the methodology outlined in previous literature59,60, in this study, we employed Question/Item 5a, “Cannot get to sleep within 30 min,” and Question/Item 5b, “Wake up in the middle of the night or early morning,” from the PSQI to assess insomnia symptoms.

Ten-item Connor–Davidson Resilience Scale

Developed by Connor and Davidson in the United States61, the 10-item Connor Davidson Resilience Scale (CD-RISC-10) is a tool for assessing an individual’s resilience level. It was later refined into a 10-item version by Campbell-Sills and Stein62. The scale uses a 5-point rating system, ranging from 0 (never) to 4 (almost always), with the total score being the sum of all item scores. Higher total scores indicate greater resilience. A previous study63 conducted by Liu has also shown that the Cronbach α coefficient of the CD-RISC-10 (Chinese version) was 0.94, and the Spearman-Brown reliability was 0.89. The total correlation of the questions ranged from 0.74 to 0.81. The exploratory factor analysis retained its single dimension, explaining 63.24% of the total variance. The CD-RISC-10 scale demonstrates acceptable reliability and validity, and is characterized by its ease of use and convenience.

KIDSCREEN-10 Index

The KIDSCREEN-10 Index survey instrument, developed by Ravens-Sieberer and colleagues in Germany64 and published in 2005, measures the health-related QoL of children and adolescents aged 8 to 18 years. The scale uses a 5-point rating system, ranging from 1 (never) to 5 (always). A higher total score indicates a higher level of QoL. This 10-item revised version demonstrated strong internal consistency (Cronbach’s α = 0.82), reliable test–retest reliability, and notable discriminant validity, making it appropriate for extensive epidemiological studies65. A previous study showed that the KIDSCREEN-10 Index was feasible and valid for measuring health-related QoL among children and adolescents in China66.

Data analysis

Initially, Harman’s single-factor test was employed to measure common method variance, thus assessing common method bias. Subsequently, IBM® SPSS® Statistics 26.0 (IBM Corp., Armonk, NY) was utilized for descriptive statistics, independent sample t-tests, and Pearson’s correlation analysis. Finally, mediation (PROCESS 4.3, Model 4) and moderated mediation model analysis (PROCESS 4.1, Model 59) were conducted using the PROCESS macro. Bootstrap testing was used to assess the mediation effects, involving 1000 resamples to estimate the 95% confidence interval (CI). Harman’s single-factor test was further applied to the variables involved for an additional examination of common method bias 67. The results revealed that there were nine factors with eigenvalues exceeding one, with the primary factor accounting for 21.3% of the variance, indicating that common method bias was not substantial. Therefore, the study did not further employ statistical methods to control for the effects of common method bias.

Ethical approval and consent to participate

The ethical standards from the 1964 Declaration of Helsinki and its later amendments were followed, and approval for this study was granted by the Ethics Committee of Beijing Huilongguan Hospital. All respondents and their guardians provided informed consent.

Results

Among the 50,666 participants, 23,687 (46.8%) were male, 30,937 (61.1%) resided in cities, and 37,633 (74.3%) reported having been infected with COVID-19. 659 (1.3%) reported having been infected with COVID-19 more than once.

Analysis of sex differences

An independent sample t-test comparing sexes showed significant differences in PTSD, resilience, insomnia, and QoL (t-values of − 26.05, 18.22, − 28.99, and 6.54, respectively; all p-values < 0.001). Consequently, sex was included as a covariate in subsequent analyses (Table 1).

Table 1 Gender difference test of the main variables of the study.
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Correlation analysis

Table 2 presents the correlations between variables. There was a significant positive correlation between COVID-19-related PTSD and insomnia (r = 0.436, p < 0.01) and a significant negative correlation between COVID-19-related PTSD and both resilience and QoL (r = − 0.176, − 0.243, p < 0.01). Insomnia showed significant negative correlations with resilience and QoL (r = − 0.205, − 0.257, p < 0.01). Resilience and QoL were significantly positively correlated (r = 0.703, p < 0.01). Additionally, age correlated significantly with PTSD, insomnia, resilience, and QoL (p < 0.01); hence, it was also controlled as a covariate in further analyses.

Table 2 Correlation analysis of research variables.
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Mediation analysis

The mediation model (PROCESS 4.3, Model 4) set QoL as the dependent variable, COVID-19-related PTSD as the independent variable, and insomnia as the mediator. After controlling for sex and age, the mediation analysis indicated that both COVID-19-related PTSD (β = − 0.16, p < 0.001) and insomnia (β = − 0.19, p < 0.001) significantly predicted QoL. COVID-19-related PTSD was also a significant predictor of insomnia (β = 0.44, p < 0.001). The indirect effect of COVID-19-related PTSD on QoL was − 0.081, with a 95% CI [− 0.088, − 0.078], suggesting that insomnia partially mediates this relationship (Fig. 2).

Figure 2
figure 2

The mediating effect of sleep problems on the relationship between COVID-19-Related PTSD and adolescent QoL. PTSD post-traumatic stress disorder, QoL quality of life. **P < 0.01.

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Moderated mediation model

In the moderated mediation model (PROCESS 4.1, Model 59), QoL and suicidal ideation were set as dependent variables, with COVID-19-related PTSD as the independent variable. Insomnia was incorporated as the mediating variable, and resilience functioned as the moderating variable. After controlling for sex and age, the results revealed that the interaction between COVID-19-related PTSD and resilience significantly predicted both insomnia (β = − 0.060, p < 0.001) and QoL (β = − 0.027, p < 0.001). Furthermore, the interaction effect between insomnia and resilience was found to significantly predict QoL (β = − 0.019, p < 0.001) (Table 3). Specifically, for individuals with high resilience, the influence of COVID-19-related PTSD on insomnia was noted with a slope of 0.443 (t = 89.905, 95% CI [0.434, 0.453]), whereas the impact on QoL had a slope of − 0.072 (t = − 16.246, 95% CI [− 0.080, − 0.063]). Furthermore, the effect of insomnia on QoL showed a slope of − 0.068 (t = − 14.809, 95% CI [− 0.077, − 0.059]). Conversely, in those with low resilience, the slope of the impact of COVID-19-related PTSD on insomnia was 0.318 (t = 47.384, 95% CI [0.305, 0.331]), that on QoL was − 0.128 (t = − 22.518, 95% CI [− 0.139, − 0.117]), and the impact of insomnia on QoL was − 0.109 (t = − 18.874, 95% CI [− 0.120, − 0.098]). These findings suggest that higher resilience can mitigate the adverse effects of COVID-19-related PTSD on both insomnia and QoL, as well as reduce the influence of insomnia on QoL. Figure 3 presents a simple slope graph that visually represents these relationships.

Table 3 Effects of PTSD on quality of life: mediating role of insomnia and modulating role of resilience.
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Figure 3
figure 3

The moderating effect of resilience on the following relationships: (A) between COVID-19-related PTSD and sleep problem; (B) between COVID-19-related PTSD and QoL; (C) between sleep problem and QoL. Res. Resilience, S.P. sleep problem, QoL quality of life, PTSD post-traumatic stress disorder.

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Discussion

In this study, we explored the underlying mechanisms through which COVID-19-related PTSD impacts the QoL among adolescents. Our findings indicate that PTSD can predict adolescents’ QoL by indirectly affecting it through insomnia and by being moderated by resilience. The results demonstrate that factors like COVID-19-related PTSD, insomnia, and resilience significantly influence adolescents’ QoL, underlining important considerations for their mental health.

Mediating role of insomnia in the link between COVID-19-related PTSD and QoL

Age and sex were controlled as covariates due to their significant impact on COVID-19-related PTSD, insomnia, and resilience, ensuring the elimination of potential external influences. The analysis revealed a strong positive correlation between COVID-19-related PTSD and insomnia. Conversely, both insomnia and COVID-19-related PTSD showed a significant negative correlation with QoL. These findings suggest that COVID-19-related PTSD directly increases the likelihood of insomnia and directly decreases QoL. Furthermore, PTSD indirectly affects QoL through its impact on insomnia. Insomnia, in turn, also directly diminishes QoL. This finding is in line with the existing literature that highlights a robust connection between PTSD and sleep disorders68,69,70,71,72,73,74.

PTSD is often linked to a reduced QoL75,76,77,78,79,80, possibly due to the high prevalence of sleep disorders in individuals with PTSD. These disorders, characterized by extended periods of poor sleep quality, can lead to decreased physical health and various other health complications, significantly impairing an individual’s overall QoL. The data support Hypothesis 1, which posits that insomnia mediates the relationship between COVID-19-related PTSD and QoL.

Moderating role of resilience in the relationship of PTSD, insomnia, and QoL

Incorporating resilience into the study demonstrates its significant negative relationship with both insomnia and COVID-19-related PTSD. Additionally, resilience exhibits a positive correlation with QoL, acting as a moderator in the relationships between COVID-19-related PTSD and insomnia and between these factors and QoL. One study found that addressing insomnia may increase resiliency and the ability to perform and cope with the complexities of active duty81. Our results reveal that resilience interacts with COVID-19-related PTSD and insomnia, impacting adolescents’ QoL, which aligns with existing research and suggests that resilience is negatively associated with PTSD50,82,83,84 and positively influences work-related QoL85,86. Moreover, QoL has been found to have a moderating role in the relationships between physical exercise and resilience87. Previous studies have shown that resilience also negatively predicted insomnia88,89. Some previous studies have shown that resilience is correlated with PTSD. EEG studies90 further showed resilience and PTSD symptoms shared meaningful similarities, which provided objective neural evidence supporting existing theory depicting PTG, resilience, and PTSD as independent—yet co-occurring—constructs. Previous studies showed that resilience mediated negative emotions91 and, consequently, QoL. Therefore, Hypothesis 2 was validated: Resilience moderates the relationships among COVID-19-related PTSD, insomnia, and QoL.

Resilience, which is considered a protective factor against various psychological issues, is a valuable sociopsychological resource. Individuals with higher resilience levels exhibit less severe COVID-19-related PTSD symptoms, lower susceptibility to insomnia, and better QoL. By contrast, those with lower resilience levels experience more severe COVID-19-related PTSD symptoms, increased likelihood of insomnia, and diminished QoL. Studies have shown that high resilience can effectively reduce symptoms associated with sleep disorders like insomnia92. Persistent insomnia can, in turn, degrade resilience. These results indicate a strong correlation between resilience levels and insomnia occurrence92. Other studies have emphasized the crucial role of resilience in influencing PTSD outcomes84.

This effect may stem from individuals with higher resilience typically employing effective cognitive-emotional regulation strategies. Emotional regulation ability is a significant predictor of adolescents’ resilience. Cognitive regulation strategies, such as positive reappraisal, predicted perceived resilience among students93. These psychological tactics aid in timely mental adjustment, reducing insomnia tendencies, and mitigating PTSD effects. Such adaptability helps alleviate negative emotional states induced by the pandemic, ultimately leading to improved QoL.

Our findings carry significant implications. They reveal a substantial correlation between insomnia and resilience with regard to COVID-19-related PTSD and quality of life in adolescents. Consequently, healthcare providers should prioritize assessing sleep quality and levels of resilience in individuals diagnosed with PTSD during pandemics. Accurate treatment of insomnia symptoms and enhancement of resilience through psychotherapeutic interventions are recommended approaches.

Limitations

The limitations of this study include its focus exclusively on the adolescent demographic, highlighting the need for further exploration of COVID-19-related PTSD, insomnia, and resilience across different age groups. Additionally, the cross-sectional design of the study limits the ability to establish causation. It is challenging to determine whether insomnia and poor resilience stem from COVID-19-related PTSD, or conversely, if they might be contributing factors to the development of PTSD associated with the pandemic. Future research necessitates a longitudinal approach and/or experimental design to rule out alternative explanations and establish clearer causal relationships. Additionally, there is a need for more in-depth investigation to identify which specific types of psychotherapy are most effective in enhancing resilience and improving sleep quality among adolescents.

Conclusion

Our findings reveal that COVID-19-related PTSD influences adolescents’ QoL both directly and indirectly through the mediation of insomnia and the moderation by resilience, which contributes to cognitive dissonance theory and the protective factor model of resilience theory. This study enhances the understanding of the effect of COVID-19-related PTSD on adolescents’ QoL. Our findings support the development of intervention and treatment strategies aimed at improving adolescent mental health, suggesting that implementing strategies to improve sleep conditions and enhance psychological resilience in adolescents with COVID-19-related PTSD may be beneficial.