INTRODUCTION
Adolescence is one of the most important periods of life, which is known as the time of change [1]. These changes include changes in the hormones of the body, changes in the social environment and brain and psychological [1]. Adolescent is defined by the World Health Organization (WHO) as “the second decade of life (10–19 years of age), a time when significant physical, psychological, and social changes occur” and as “a unique stage of human development and an important time for laying the foundations of good health” [2,3]. The adolescent population is 1.3 billion and this is 16% of the world population [4]. Although young people pass through adolescence and enter adulthood, adolescence is a period when and face mental health problems [1]. According to the changes that occur during adolescence, there are mental health problems in adolescents and the prevalence of mental disorders was 13.4% [5]. One of the mental health problems in adolescence is sleep problems [6].
Sleep is vital to growth [7], tissue restoration [8], and health dimensions [9]. Sleep problems affect many people around the world [10]. Sleep disorders include several types of conditions affecting sleep [11]. Sleep disturbance affects 45% of people around the world and has emerged as a health problem [12,13]. General sleep disturbance prevalence rates have been reported as 32% [14]. Sleep has a wide range of effects on health [8,15,16]. Sleep quality is measured using one’s satisfaction with sleep experience, quantity of sleep, and continuity of sleep [17]. Poor sleep quality, short sleep duration, and insomnia are more prevalent in night-shift workers [18]. Sleep is associated with health, and current recommendations are for adults aged 18–60 years, to have at least 7 hours of sleep per day [19,20]. Many studies have investigated sleep problems in adolescents [21,22]. One of the important factors in sleep problems is cognitive emotion regulation strategies [23,24].
The adaptive management of emotions is critical for psychological well-being [25,26]. Emotion regulation contains “the extrinsic and intrinsic processes responsible for monitoring, evaluating, and modifying emotional reactions, especially their intensive and temporal features, to accomplish one’s goals” [27]. There are individual differences in emotional abilities, including identifying and understanding own and others’ emotions, the causes and outcomes of different emotions, and strategies used to regulate emotions [28,29]. Maladaptive cognitive emotion regulation strategies are associated with mental health problems such as depression and anxiety [25,30-32]. In this regard, it has been shown that emotional strategies affect sleep [33-35]. In addition to the effect of cognitive emotion regulation strategies on sleep quality, another factor in this relationship is lifestyle [36].
Lifestyle is a complex concept and there are many definitions [37]. One definition of lifestyle is “a pattern of repeated acts that are both dynamic and to some degree the individual is oblivious to, and which involves the use of artifacts” [38]. Lifestyle can range from healthy to unhealthy, and studies have shown that an unhealthy lifestyle can affect health for example metabolic syndrome, all-cause mortality, cardiovascular disease, health-related quality of life, and depression [39-42].
Lifestyle and cognitive emotion regulation strategies have an impact on different dimensions of physical and mental health and as stated in the previous sections, there is a relationship between both of these with sleep quality [43-45]. As the scientific evidence around this issue is widespread, we do not know the impact of the interaction between lifestyle and cognitive emotion regulation strategies on sleep quality. Another issue that is important is the period of adolescence, this period is characterized by many changes in lifestyle and emotions, and therefore it is a challenging period of life that is different from other periods of life. And due to psychological, physiological, and emotional changes, it is necessary to investigate further.
The current study investigated the relationships between adaptive and maladaptive cognitive emotion regulation strategies with poor sleep quality. It was hypothesized that there would be a negative and positive association between adaptive and maladaptive cognitive emotion regulation strategies with poor sleep quality respectively. Also, the relationship between health-promoting lifestyle and poor sleep quality was followed as another goal of this research. However, considering that this study was conducted on adolescents and also the changes that occur during adolescence, the main goal of this research was to investigate whether lifestyle can mediate the relationship between cognitive emotion regulation strategies and sleep quality.
METHOD
Study Design and Population
This cross-sectional study, which investigated the relationship between lifestyle, emotion regulation, and sleep quality, was conducted in Iran between December 2023 and March 2024. The target population was adolescent girls between 12–18 years old. The present study was multicenter, involving five secondary schools. The study was carried out face-to-face in these schools. The first author talked to the teenagers about the purpose of the research in a group and asked them to participate in the research if they were satisfied. Also, the first author was actively present and answered the ambiguity in the understanding of each of the items. A total of 318 adolescents participated in this study in person, and after cleaning up the data, 282 had enough data to be included in this research.
Ethical Considerations
This research was based on the ethical principles presented in the Declaration of Helsinki [46] and was also approved by the Ethics Committee of the Islamic Azad University (IR.IAU. SRB.REC.1402.306). Before commencing the study, informed consent was obtained from all participants (from parents, students, and school administrators), ensuring adherence to ethical standards. In this way, to conduct this study, an informed consent form was provided to the participants (also students and school administrators), and also the researchers explained the purpose of the research in person, and the participants were asked to participate in this study, and in case of unwillingness, there was no forced cooperation. The participants were assured that the answers would be completely confidential and anonymous.
Sample Size
The sample size for this research was calculated using G*Power software [47]. Based on a null hypothesis correlation (PH0) of 0, an alternative hypothesis correlation (PH1) of 0.2, an alpha error probability of 0.05, and a power of 0.95, the required sample size was determined to be 266.
Eligibility Criteria
In this research, the Population, Intervention, Comparison, Outcomes, and Study design (PICOS) framework [48] was applied, with each component detailed as follows: 1) The population consisted of adolescent girls aged 12–18 years; 2) The exposure variables were health-promoting lifestyles and cognitive emotion regulation; 3) Due to the nature of this research, there was no comparison group; 4) The outcome measured was sleep quality, which was analyzed both as a continuous variable and as a binary variable (good vs. poor); and 5) The study employed a cross-sectional design over a four-month period, conducted in person. The exclusion criteria for this study were adolescents with serious mental disorders or physical diseases. The mental disorder or physical illness considered in this research were those disorders that were reported by the family or teenagers and had a diagnostic file. Therefore, simply answering yes or no to the history of mental disorders and physical illness was not enough for diagnosis, and it was necessary to provide more detailed information from the family. Students over the age of 18 years were not eligible, even if they were in adolescent high schools.
Study Instruments
Sociodemographic
A demographic questionnaire was created to collect information. This paper examined these items age, height, and weight to calculate BMI based on percentile [49], underweight >5th percentile, healthy weight 5th percentile–85th percentile, overweight 85th percentile–95th percentile, obesity 95th percentile or greater [50]. The demographic questionnaire also measures education level (what grade are you), employment status (“I also work” vs. “I am only a student”), family economic status (very excellent, excellent, good, moderate, poor), number of family members (2, 3, 4, 5, 6 or more), history of disease (yes vs. no), history of any drug use (yes vs. no), and living situation (Who do you live with?; both parents, father, mother, grandfather and grandmother, other).
Health-promoting lifestyle profile
Health-promoting lifestyle has 52 items that measure lifestyle. This questionnaire was developed by Walker et al. [51]. The items of this questionnaire include six dimensions of lifestyle: health responsibility, spiritual growth, physical activity, interpersonal relationships, nutrition, and stress management. The scoring of this questionnaire is on a four-point Likert scale 1 (never), 2 (sometimes), 3 (often), and 4 (routinely). The minimum score obtained in this questionnaire is 52 and the maximum score is 208. Higher scores indicate more promoting lifestyle behaviors [51]. This questionnaire has good psychometrics and in the original version, Cornbrash’s alpha for the questionnaire was reported as 0.94, and for the subscales, Cornbrash’s alpha was between 0.79 and 0.87 [51]. According to the study, a score between 52–104 is classified as a poor lifestyle, 105–156 as a moderate lifestyle, and a score between 157–208 as a good lifestyle [52].
Pittsburgh Sleep Quality Index
The Pittsburgh Sleep Quality Questionnaire is a self-report scale of sleep quality and quantity that has 19 items [53]. This questionnaire has a total of seven components, which include: subjective sleep quality (1 item), sleep latency (2 items), sleep duration (1 item), sleep efficiency (3 items), sleep disturbances (9 items), use of sleeping medication (1 item), and daytime dysfunction (2 items). Higher scores in this questionnaire indicate poorer sleep quality [53]. A score higher than 5 is considered the cutoff point for poor sleep quality [53]. This questionnaire has been used in different cultures and it has also been used in different populations and it shows that the psychometric dimensions of this questionnaire are valid [54-58].
Cognitive Emotion Regulation Questionnaire
This questionnaire was developed to measure cognitive emotion regulation strategies [59]. This questionnaire is a shortened version of 36 items that was developed in 2001 [60]. Like the 36-item version, this questionnaire has 9 dimensions: self-blame, other-blame, rumination, catastrophizing, putting into perspective, positive refocusing, positive reappraisal, acceptance, and planning. The scoring of each item is based on a 5-point Likert scale of 1 (almost never) to 5 (almost always). In total, there are two main components including adaptive and maladaptive cognitive emotion regulation strategies. Higher scores mean more use of cognitive emotion regulation strategies. The Cronbach’s alpha coefficient of the subscale was at an acceptable level, and the alpha coefficient was between 0.68 and 0.81 [59]. Extensive studies in different cultures and populations have shown the psychometric characteristics of this questionnaire [61-64].
Statistical Analysis
First, the descriptive indicators related to the participants in this research were analyzed. After collecting the data based on the guidelines for scoring each of the questionnaires, the scores related to each component were combined. Pearson’s correlation coefficient was first used to check the relationships between research variables. Next, linear regression was used to draw predictive relationships based on independent and dependent variables. To investigate the mediator variable, path analysis was used and the result of the Sobel test was used [65]. To analyze the data, SPSS version 22 (IBM Corp., Armonk, NY, USA) and LISREL 8.8 [66] were used.
RESULTS
The demographic variables collected from the participants in this study are listed in Table 1. A total of 282 adolescents participated in this study, whose age range was between 12–18 years, with a mean and standard deviation of 15.16±1.55 years. The prevalence rate of overweight and obesity is equal to 14.2% and 4.3%, respectively.
Table 2 shows the mean, standard deviation, and other descriptive indicators of each of the variables studied in this research including the Pittsburgh Sleep Quality Index, health-promoting lifestyle, and adaptive and maladaptive cognitive emotion regulation strategies. Descriptive statistics related to the subscales of each variable are listed in Supplementary Table 1 (in the online-only Data Supplement).
Correlation Analysis
To understand the relationship between research variables, the Pearson correlation coefficient was used, and the correlation results among the Pittsburgh Sleep Quality Index, health-promoting lifestyle, and adaptive and maladaptive cognitive emotion regulation strategies are shown in Table 3.
Table 3 shows Pearson’s correlation coefficient between research variables. Correlation results show that a health-promoting lifestyle has a negative relationship with poor sleep quality (r = -0.306; p < 0.01). That is, by increasing the health-promoting lifestyle, poor sleep quality improves. Also, the relationship between maladaptive cognitive emotion regulation strategies and poor sleep quality was a positive direct correlation (r = 0.388; p < 0.01). This means that with the increase of maladaptive emotion regulation strategies, poor sleep quality also increases. The relationship between adaptive cognitive emotion regulation strategies and poor sleep quality was negative but non-significant (r = -0.090; p = 0.131). Supplementary Tables 2 and 3 (in the online-only Data Supplement) show the correlation between health-promoting lifestyle components and cognitive emotion regulation strategies with poor sleep quality.
Regression Analysis
Linear regression was used to draw the prediction model for poor sleep quality according to lifestyle profile, and adaptive and maladaptive cognitive emotion regulation strategies.
Table 4 shows the simple linear regression model between predictor and outcome variables. The obtained result showed that F was 26.07 and showed the significance of the model. The R2 showed that 22% of the variance of poor sleep quality was explained by the predictor variables. Among of predictor variables in the model, health-promoting lifestyle profile and maladaptive strategies were significant and predicted poor sleep quality.
Mediation Analysis
Path analysis was used to draw a mediation model between adaptive and maladaptive emotion regulation strategies and poor sleep quality based on the mediating role of health-promoting lifestyle.
Fig. 1A showed a mediating role of health-promoting lifestyle in the relationship between adaptive emotion regulation strategies and poor sleep quality, it was significant, the coefficient of the indirect path was equal to -0.18 and the Sobel test was equal to -4.68. Sobel test is significant when it is ±1.96.
Fig. 1B showed a mediating role of health-promoting lifestyle in the relationship between maladaptive emotion regulation strategies and poor sleep quality, it was non-significant, the coefficient of the indirect path was equal to 0.03 and the Sobel test was equal to 1.84. Sobel test is significant when it is ±1.96.
DISCUSSION
Research evidence shows that emotion regulation deficits are associated with a wide range of psychopathological outcomes [25,67,68]. The relationship between emotion regulation and psychological damage has important implications in the level of theoretical and practical of emotion regulation and at prevention and treatment of psychological damage in adolescents [69,70]. The models of emotion regulation suggest that emotion regulation involves processes related to the evaluation and interpretation of emotional situations, the modification of emotional information, and emotional experiences [70,71].
The current study aimed to examine whether lifestyle helps explain the mediation between adaptive and maladaptive emotion regulation strategies with poor sleep quality. The results obtained for this research showed that maladaptive emotion regulation strategies are related to increasing poor sleep quality, and in other words, adolescents who use negative emotion regulation strategies are more exposed to sleep disorders. The obtained findings are consistent with studies that have shown a positive relationship between maladaptive cognitive emotion regulation strategies with sleep quality [35,72,73]. The relationship between adaptive cognitive emotion regulation strategies and poor sleep quality was negative but non-significant. On the other hand, the important finding of the present study showed that the use of a health-promoting lifestyle in adolescents is an inhibitory factor against poor sleep quality. That is, having a healthy lifestyle is related to increasing sleep quality. This finding is consistent with studies that have tried to show the relationship between a healthy lifestyle and sleep quality [74,75].
What was important in the findings of the current study was that health-promoting lifestyle had a central and mediating role in the relationship between adaptive and maladaptive cognitive emotion regulation strategies with poor sleep quality. In general, there was no direct relationship between adaptive strategies of cognitive emotion regulation with poor sleep quality, when a health-promoting lifestyle was entered as a mediator, a significant negative relationship between adaptive cognitive emotion regulation strategies and poor sleep quality emerged. On the other hand, the direct and significant relationship that existed between cognitive-emotional regulation strategies and poor sleep quality disappeared with the inclusion of lifestyle as a moderating variable. What can be obtained from this finding is that the cognitive emotion regulation strategies alone cannot be related to the quality of sleep and what has a more important and central role is the lifestyle. As defined, cognitive emotion regulation strategies refer to the “conscious, cognitive way of handling the intake of emotionally arousing information” [76], and in a broader format emotion regulation is defined as “all the extrinsic and intrinsic processes responsible for monitoring, evaluating, and modifying emotional reactions, especially their intensive and temporal features” [27,77]. Therefore, emotional regulation is mostly used in emotion-provoking situations and includes most of the temporary conditions, this is in contrast to lifestyle, which consists of a set of behaviors over a long period. For example, it has been shown that emotional dysregulation can contribute to the initiation and maintenance of an unhealthy lifestyle under stressful conditions [78,79]; therefore, the interaction between lifestyle and emotional regulation can be much more complex, and individual, emotional, and transformational differences should be considered.
The current research was a cross-sectional study and it is not possible to extract causal relationships from it, and it also only included adolescent girls, and this is a limitation. The current study is one of the limited studies that have investigated the mediation relationship of lifestyle and therefore it is an important strength in this respect. It is necessary to conduct cohort studies in future studies.
In conclusion, current research has shown that cognitive emotion regulation strategies are related to poor sleep quality and this effect is mediated by a healthy lifestyle. Therefore, the role of lifestyle in poor sleep quality seems to be more important than cognitive emotion regulation strategies, perhaps because health-promoting lifestyles have longer-term effects on health.
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