The self-rated health of 1,762 adults living in urban areas in Brazil during the COVID-19 pandemic was evaluated in this study. Sleep quality was associated with self-rated health, and anxiety and depression partially mediated this association, explaining about one-fifth of the effect of sleep on self-esteem. Mental disorders may act as mechanisms through which sleep affects health during the COVID-19 pandemic, according to these findings.
Our results are from previous studies that have shown a negative association between sleep quality and self-rated health in different populations 14. The COVID-19 pandemic may have exacerbated this relationship, with changes in people's sleep habits and routines 1,26. Sleep quality can influence self-rated health through various physiological, psychological, and social mechanisms. As previously described, lack of sleep affects various aspects of health, including immunity, metabolism, and mental well-being. This can lead to chronic diseases, affect mood and cognition, and impair social relationships. Therefore, our findings underscore the importance of addressing sleep quality for overall health and well-being 11,27.
The connection between sleep quality and self-assessed health could be attributed to mental well-being. The rhythms of the night control hormones, neurotransmitters, and cytokines that affect mood, cognition, and stress. The risk of anxiety and depression can be increased by lack of or poor quality sleep 28. In addition, anxiety and depression can decrease self-esteem, self-efficacy, motivation, and hope, as well as increase pessimism, social isolation, and psychological distress, leading to a negative perception of health 29. This hypothesis about the possible mechanisms underlying the connection between sleep quality and self-assessed health was confirmed by the mediation analysis. The indirect effect of sleep quality on self-rated health was mediated by symptoms of anxiety and depression. The sleep hygiene hypothesis suggests that good sleep quality promotes emotional well-being and prevents the development of mental disorders 30. Conversely, poor sleep can negatively affect people's mood, cognition, and daily functioning, increasing the risk of anxiety and depression 31. These mental disorders, in turn, can damage self-rated health, causing psychological distress, low self-esteem, social isolation, and worsening physical health 32,33.
There is a gap in the literature that seeks to understand the mediation of mental health in this association, which is why the results are innovative. In a study by Zhu et al. (2023), they assessed the association between sleep quality and self-rated health and examined whether depressive and anxious symptoms can explain/mediate this association. This study found evidence that symptoms of anxiety and depression partially mediated the effect of the association between poor sleep quality and self-rated health 34. Several other studies have also shown that individuals with psychological health disorders tend to report a worse state of health 12,35,36.
The COVID-19 pandemic may have influenced the relationships observed between sleep quality, mental health, and self-rated health. The pandemic caused a series of stressors for people, such as fear of contagion, social isolation, loss of income, bereavement, uncertainty, and changes in routine 37. These stressors can negatively affect sleep quality, increasing difficulty falling asleep or staying asleep, reducing total sleep time, or altering circadian rhythms 38. These stressors can also negatively affect mental health, increasing levels of anxiety and depression in the population 39. In addition, the pandemic may have negatively affected self-rated health, reducing people's perception of physical and emotional well-being 40. It is therefore possible that the pandemic has exacerbated the impact of poor sleep on mental health and, consequently, on self-rated health. However, we cannot say that the pandemic is the only cause of these associations, as other factors can influence them. For example, genetic, environmental, behavioral, and social factors can affect sleep as well as mental health and self-rated health 41,42.
Our findings hold significance for public health interventions and clinical practice, particularly in the context of pandemic response and recovery. Our findings indicate that it is imperative to acknowledge the correlation between sleep quality, mental health, and self-rated health when devising targeted interventions. Sleep quality improvement can have benefits for people's mental health and self-rated health. Therefore, we recommend implementing strategies to improve the population's sleep habits, such as maintaining a regular sleep routine, avoiding the use of alcohol, caffeine, and nicotine before bedtime, reducing exposure to artificial light at night, creating a comfortable and quiet environment for sleep, and seeking professional help in case of chronic sleep problems. Some examples of treatments that can enhance sleep quality and mental health include cognitive-behavioral therapy, sleep hygiene, meditation, physical exercise, pharmacotherapy, and psychotherapy.
Despite the methodological efforts made to guarantee the validity and reliability of our results, we recognize some limitations of our study, which should be taken into account when interpreting the findings. Initially, the cross-sectional design does not permit us to establish causal relationships between variables but rather establish associations. Therefore, we cannot claim that sleep quality causes self-rated health, nor that anxiety and depression are the only mediators of this relationship. It is plausible that additional factors exert an impact on both sleep and self-rated health, or that there exists a reversible or bidirectional correlation between the two. To clarify these issues, it is imperative to conduct longitudinal studies that follow participants over time and evaluate changes in sleep quality, self-rated health, and symptoms of anxiety and depression. It is important to consider the possibility of information bias arising from the use of self-administered questionnaires. Participants may have answered the questions based on their memories, perceptions, or expectations, which may have led to errors or distortions in the measurements of the variables. Furthermore, the questionnaire may not capture all the nuances and complexities of sleep quality, self-rated health, and symptoms of anxiety and depression.
A representative random sample of the resident population from different socioeconomic strata, assessment through a household survey, and face-to-face interviews during the COVID-19 pandemic are some strengths that should be mentioned. To support the assumptions of the analysis, the hypotheses were carefully defined according to current scientific literature and articulated in counterfactual terms. In this sense, the inclusion of directed graphical models is of great importance and provides robustness to the study. In this sense, the incorporation of directed graphical models is of great importance and provides robustness to the study.