Introduction

The World Health Organization declared the coronavirus disease (COVID-19) pandemic in March 2020. South Korea subsequently implemented strict initial containment measures, successfully curbing the early spread of COVID-19. However, these policies led to unavoidable psychosocial and economic challenges. In particular, mental health issues, including isolation, lethargy, and depression, became increasingly prevalent due to uncertainty during this period1,2, followed by physical health deterioration, weight gain3, and economic impacts, such as rising unemployment4. By the end of 2020, South Korea’s household debt had increased to 1,726 trillion KRW, representing a 7.9% increase since 2019, with a debt ratio of 209.8% recorded in 20215.

The sudden economic hardship and ongoing uncertainty resulted in increased anxiety and worry among parents as well as adolescents who were spending more time with them6. Social distancing and the transition to online education increased the amount of time young individuals spend at home, exacerbating psychological challenges in vulnerable populations, particularly adolescents, resulting in heightened anxiety, worry, depression, and fatigue1,2,7. However, research on how these psychosocial factors have affected the health behaviors of Korean adolescents remains limited.

Economic hardship is a significant social determinant influencing mental health inequalities among children and adolescents8,9, which also affects behavior and language functions10. Adolescents’ perceptions of their family’s financial difficulties are frequently linked to the objective economic situation of their household while also reflecting the psychological weight of these circumstances11. Consequently, parents experiencing financial strain may perceive that such stress directly influences the mental health of their children beyond material deprivation12. For example, during the economic recession in Finland, the psychological well-being of children deteriorated and was influenced by family interactions13. According to the Family Stress Model, financial hardship leads to economic pressure and subsequently contributes to parental psychological distress. This distress may manifest as marital conflict and result in compromised parenting behaviors. Such disruptions in parenting are associated with children’s maladjustment, including increased aggression, anxiety, depression, deteriorating physical health, overweight status, and impaired self-regulation14. These factors are closely linked to adolescents’ sleep outcomes15.

These psychological issues can impact sleep in adolescents. Notably, sleep plays an important role in restoring bodily functions and managing stress, particularly during the developmental phase of adolescence. Adolescents experiencing mental health issues such as anxiety, depression, and stress often report poor sleep quality, including difficulty falling asleep, waking during the night, or taking longer to fall asleep16. During the COVID-19 pandemic, 20% and 27.5% of middle and high school girls, respectively, in South Korea reported experiencing insomnia17. Similarly, a study in Italy revealed that the pandemic negatively affected the sleep habits of adolescents, leading to psychological distress and insomnia18.

Economic difficulties are also a fundamental cause of disparities in sleep quality and duration19,20. A study from Brazil reported that individuals earning below the minimum wage, unemployed individuals, and those experiencing significant income loss were twice as likely to experience worsening sleep problems21. Sleep in adolescents is closely related to socioeconomic factors. Specifically, economic difficulties can exacerbate psychological challenges, lifestyle changes, and physical activity, all of which adversely affect sleep health22,23.

Nevertheless, comprehensive research examining the impact of financial stress on adolescent sleep quality and duration in South Korea is lacking. Existing studies in South Korea have focused primarily on the relationships between economic difficulties and mental health outcomes (e.g., suicidal ideation and anxiety)22,24 and health risk behaviors (e.g., smoking, alcohol consumption) among adolescents24. However, few studies have comprehensively analyzed the effects of financial stress on sleep among adolescents.

Understanding how financial stress experienced by families affects sleep patterns in adolescents, particularly when they spend extended periods at home, is essential for elucidating the relationship between sleep health and overall health behaviors. Such research can provide valuable insights for developing guidelines tailored to behavioral responses among adolescents during crisis situations.

Therefore, this study aimed to investigate the relationship between financial hardships experienced by families and adolescents’ sleep patterns—specifically sleep duration and subjective sleep quality. Based on the family stress model, we hypothesized that perceived financial hardship would be significantly associated with abnormal sleep patterns among adolescents.

Results

Table 1 presents the general characteristics of the study population. Among the 95,816 participants, 12,129 male students (50.2% of the 49,590 male participants) reported that their household financial situation had worsened due to COVID-19, whereas 3,062 (12.7%) reported that it was very difficult. Among the male students who reported their household financial situation as very difficult, 61.4% slept < 7 h per day, whereas 5.8% slept > 9 h.

Table 1 General characteristics of the study population.
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Among the 46,226 female students, 11,476 (51.4%) reported that their household financial situation had worsened, whereas 2,268 (10.2%) reported it was very difficult. Among the female students who reported their household financial situation as very difficult, 76.5% slept < 7 h per day, whereas 3.3% slept > 9 h. Chi-square analysis revealed significant differences in sleep duration based on perceived household financial difficulty due to COVID-19, grade, academic level, region, household income, type of residence, depressive symptoms, smoking, and stress in males and females.

Table 2 presents the results of the multinomial logistic regression analyses stratified by sex after adjusting for grade, academic level, region of residence, household income, type of residence, depressive symptoms, exercise, smoking status, alcohol consumption, smartphone use, and stress. Compared with those without financial difficulties, female students who reported financial difficulties had significantly greater odds of sleeping for < 7 h (odds ratio [OR]: 1.14, 95% confidence interval [CI]: 1.01–1.29) and significantly greater odds of sleeping for > 9 h (OR: 1.52, 95% CI: 1.16–1.99). In male students, a trend toward increased odds of sleeping for < 7 h (OR: 1.10, 95% CI: 1.00–1.22) or > 9 h (OR: 1.20, 95% CI: 0.99–1.45) was observed with worsening financial hardship, although the difference was not statistically significant. In both sexes, higher grade levels were associated with significantly increased odds of sleeping for < 7 h and significantly decreased odds of sleeping for > 9 h. Alcohol consumption was associated with increased odds of sleeping for < 7 h in both male (OR: 1.25, 95% CI: 1.19–1.31) and female (OR: 1.26, 95% CI: 1.19–1.34) students.

Table 2 Results of factors associated with sleep duration using multinomial logistic regression.
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Perceived stress was a significant predictor of reduced sleep duration, with both male (OR: 1.53, 95% CI: 1.46–1.60) and female (OR: 1.65, 95% CI: 1.55–1.75) students reporting higher odds of sleeping for < 7 h.

Table 3 presents the results of the subgroup analysis that examined the relationships among academic performance, health behaviors, economic hardship, and sleep duration. In individuals with above-average academic performance, significant economic difficulties due to COVID-19 were associated with reduced or increased sleep duration. In this group, the ORs for males and females sleeping excessively were 1.42 (CI: 1.06–1.90) and 1.89 (CI: 1.18–3.02), respectively, indicating a stronger impact on female students.

Among female students, nondrinkers and nonsmokers reporting significant economic distress presented marginally significant increases in the odds of decreased sleep duration (smoking: OR: 1.16, CI: 1.02–1.33; alcohol: OR: 1.20, CI: 1.03–1.39). Conversely, the likelihood of increased sleep duration was also greater for these students, with ORs of 1.62 (CI: 1.24–2.12) and 1.77 (CI: 1.34–2.36) for smokers and alcohol consumers, respectively.

Table 3 Subgroup analysis stratified by independent variables.
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Figure 1 illustrates a pseudo U-shaped relationship between extreme household financial hardships and sleep duration. Male students who perceived their household financial difficulty as very severe were more likely to have a short sleep duration of < 5 h (OR: 1.22, CI: 1.05–1.42) than those without household financial difficulty. Furthermore, female students who perceived their household financial difficulty as serious were less likely to sleep for > 10 h (OR: 1.55, 95% CI: 1.17–2.05) or < 5 h (OR: 1.22, CI: 1.03–1.44) than were those without household financial difficulty.

Fig. 1
figure 1

Dependent subgroup analysis stratified by sleep duration. †Statistically significant results (p < 0.05).

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Table 4 presents sleep satisfaction stratified by sleep duration. Overall, the odds of sleep dissatisfaction were notably higher. Specifically, among male students, the odds of dissatisfaction with normal sleep increased significantly with greater perceived economic hardship (OR: 1.41, CI: 1.17–1.70). For female students, significant increases in the odds of dissatisfaction were observed for both short sleep duration (OR: 1.33, CI: 1.11–1.59) and normal sleep (OR: 1.41, CI: 1.10–1.81) as the perception of economic difficulty intensified.

Table 4 Subgroup analysis stratified by sleep satisfaction.
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Discussion

This study investigated the associations between perceived financial hardship due to COVID-19 and sleep duration. The findings indicate that students who perceived their households as financially strained because of the pandemic were more likely to experience reduced or increased sleep duration. Importantly, the severity of financial hardship was associated with a greater likelihood of abnormal sleep patterns. Additionally, these patterns differed in intensity between male and female students, with female students exhibiting a stronger association between financial hardship and both reduced and increased sleep. This relationship remained significant even after adjusting for demographics, health behaviors, and mental health factors. Notably, severe financial hardship affects both the quantity and quality of sleep25. Adolescents facing financial difficulties may experience stress, which contributes to anxiety and depression and disrupts sleep patterns, ultimately adversely affecting developmental outcomes20.

These findings can be interpreted within the framework of the Family Stress Model. According to this model, economic hardship increases parental psychological stress, which in turn leads to negative family interactions such as conflict and emotional distancing. These dynamics ultimately affect children’s sleep and overall health outcomes14,15. Previous research has consistently demonstrated an association between financial stress and adverse sleep outcomes. Several studies report that financial hardship is correlated with reduced sleep duration and diminished sleep quality19,26. A South Korean study indicated that household income significantly influences sleep duration in adolescents and that children from higher-income families tend to have shorter sleep durations27. However, our study found that adolescents perceiving severe financial difficulty—especially females—were more likely to report both insufficient and excessive sleep. This divergence from prior findings may be attributed to the unique context of the COVID-19 pandemic. Adolescents may have perceived the pandemic as a highly uncertain and uncontrollable event, which could have adversely affected their mental health by increasing psychological stress. Such conditions may have contributed to the disruption and polarization of their sleep patterns28.

Early reports from Europe and China during the COVID-19 pandemic highlighted widespread sleep disturbances, with financial stress being a notable factor associated with poor sleep health29. Furthermore, in the United States, financial difficulties arising during the pandemic were correlated with increased rates of sleep disorders, particularly among women19.

Interestingly, students with average or above-average academic performance were more likely to experience excessive sleep under financial stress. These findings suggest that excessive sleep may serve as a coping mechanism for managing or avoiding stress30,31. Existing research suggests that excessive sleep under financial stress may reflect a coping mechanism. For instance, Özkan and Bostan (2022) found that students perceiving higher financial stress tended to sleep longer, which was interpreted as a behavioral symptom of stress-related avoidance32. Additionally, students who did not smoke or consume alcohol were more likely to experience both insufficient and excessive sleep under financial stress, indicating the need for further research on this demographic. Male students from households with relatively high socioeconomic status who perceived severe financial difficulties during the pandemic presented an increased risk of insufficient sleep, suggesting that sleep disturbances may stem not only from persistent economic challenges but also from sudden financial crises.

Our findings revealed that responses to economic stress manifested as both insufficient and excessive sleep among adolescents, with these patterns differing according to sex. Therefore, excessive sleep, as well as insufficient sleep, may serve as an indicator of stress in adolescents. During adolescence, insufficient sleep is associated with numerous negative outcomes, including reduced academic achievement, mental health issues, risky behaviors, substance use, and weight gain33,34. Although insufficient and excessive sleep are often linked to cognitive impairment and dementia in adults35,36, studies on their health implications among adolescents are lacking. Consequently, further studies are needed to explore excessive sleep as a response to stress and examine its potential health impacts on adolescents.

The sleep satisfaction among adolescents exhibited an overall decline, with an average sleep duration of 6.99 h, which was below the National Sleep Foundation’s recommended 8–10 h of sleep37, likely contributing to low sleep satisfaction. Additionally, severe financial stress was found to significantly impact higher levels of sleep dissatisfaction. Further stratification by sleep duration revealed that severe financial stress significantly impacted higher levels of sleep dissatisfaction, indicating that financial stress affects both short and long sleepers and plays a critical role in influencing both sleep quantity and quality38.

Social distancing measures and remote learning resulted in adolescents spending more time at home with family members39, increasing their awareness of the household’s financial situation. In effect, financial stress extends beyond parental concern, emerging as a household issue that significantly impacts the psychological well-being of adolescents. Although they may have been aware of their family’s general economic status, the unforeseen financial repercussions due to the pandemic likely triggered anxiety and stress, directly affecting their sleep patterns and quality17,40,41.

Sudden economic stress is not only a temporary disruption but also a significant stressor affecting the health and well-being of adolescents. Stress stemming from financial hardship may further impair sleep and health, warranting additional research on long-term effects. This study emphasizes the wide-ranging impact of economic stress on the sleep of adolescents and the need for public health interventions to mitigate these adverse effects.

This study also has some limitations. First, the cross-sectional design of this study limits its ability to establish causality between financial difficulties and sleep duration. While associations were identified, the temporal order of events cannot be determined, and thus causal inferences should be made with caution. Future research using longitudinal or experimental designs would provide greater clarity on the directionality of these relationships.

Second, the survey relied on adolescent perceptions rather than objective measures of economic hardship. Future studies should incorporate objective economic data to better understand the effects of the pandemic. Third, owing to the measurement differences, direct comparisons of this study with studies from other countries and the generalization of our findings to different contexts or populations may not be feasible. Finally, the sleep data in this study were limited to weekdays; however, prior research indicates that insufficient sleep during the week can often be compensated for on weekends42. Nevertheless, given that middle school education is mandatory in Korea and that the study utilized a stratified sampling approach on the basis of region and population size, the risk of selection bias was minimal.

Nonetheless, our study also has several strengths. It utilized a nationwide dataset representing the health of Korean adolescents, enabling a robust stratified analysis by sex, region, and grade level supported by a large sample size. Additionally, this study includes data from both 2020 and 2021, capturing the perceptions of adolescents related to financial difficulties due to COVID-19 and the persistence of these challenges.

This study revealed that the likelihood of experiencing both insufficient and excessive sleep increased as students increasingly perceived their households as financially strained due to COVID-19, with distinct sleep patterns between male and female students. Furthermore, the severity of financial hardship was correlated with an increase in abnormal sleep patterns, underscoring the necessity for policy interventions aimed at supporting student growth and well-being. Future research should explore the relationship between psychological stress originating from the household or parents and the risks associated with insufficient and excessive sleep to gain a more comprehensive understanding of the potential health implications.

Methods

Data sources and samples

This study used data from the 16th and 17th Korea Youth Risk Behavior Surveys (KYRBS) of 2020 and 2021. The KYRBS is an annual, nationwide cross-sectional survey of a representative Korean youth population conducted by the Korea Disease Control and Prevention Agency (KCDC) since 2005. Participants ranged from 7th to 12th grade, with the majority aged between 13 and 18 years. The self-reported online survey of middle and high school students was conducted between August and November in 2020 and 2021. The primary objective of the KYRBS is to assess the socioeconomic and health statuses and behaviors of adolescents to generate internationally comparable health indicators. The sampling framework involved stratification by 39 regional and school-type categories (middle school and high school), with cluster sampling at the school and class levels. This study used raw data from the KYRBS, a government-approved statistical survey (approval number 117058) conducted by the KDCA. The anonymized raw data were obtained and downloaded from the KDCA website. As a government-approved statistical survey, the KYRBS collects data only after obtaining informed consent from all participants prior to the survey. Since the KYRBS data are publicly available secondary data, this study did not require additional review by an Institutional Review Board (IRB).

In 2020, the target population included 2,631,888 students, from which a sample of 54,948 was drawn (28,353 males and 26,595 females; response rate, 94.9%). In 2021, the target population was 2,629,588, with a sample of 54,848 students (28,401 males and 26,447 females; response rate, 92.9%). After individuals with missing data on key variables were excluded, the final sample for this study included 95,816 students.

Variables

The dependent variable was sleep duration, which was calculated as the difference between bedtime and wake-up time on weekdays. Sleep duration was self-reported through questions such as “What time do you usually go to bed on weekdays?” and “What time do you usually get up on weekdays?” The participants were categorized into three groups: <7 h of sleep (short-time sleeper), 7–9 h of sleep (moderate sleeper), and > 9 h of sleep (long-time sleeper).

The independent variable was perceived household financial difficulty due to COVID-19. This variable indicates the psychological impact of the economic decline at home caused by the pandemic on adolescents. The response pertaining to a decrease in household finances due to the pandemic was generally categorized as “yes” or “no” and was specifically classified as “no financial decline,” “inappreciable financial decline,” “moderate financial decline,” or “substantial financial decline.” Data on this variable were collected only for the 2-year period, spanning from 2020 to 2021.

The covariates were demographic and socioeconomic variables (sex, school grade, household income, academic level, residential area (metropolitan, urban, or rural), type of residence (living with family or not), mental health-related variables (perceived stress and depressive symptoms), and health behavior variables (exercise, smoking, and smartphone usage).

Statistical analysis

The chi-square test was used to evaluate and compare the general characteristics of the study population. Multinomial logistic regression was used to examine the associations between household financial hardship due to COVID-19 and sleep duration. Subgroup analyses were conducted to investigate the combined effects of perceived household financial difficulty and other covariates on sleep duration. The results are presented as ORs with 95% CIs. No multicollinearity was found in any of the variables when the variance inflation factor was used. Statistical significance was set at P ≤ 0.05. Statistical analyses were performed using SAS, version 9.4 (SAS Institute Inc., Cary, North Carolina, US).