1. Introduction
From the data made public by the World Health Organization in 2022, we can learn that 1 billion people in the world suffer from mental disorders, accounting for about one-eighth of the global population. Of these, about 240 million people suffer from depression and 374 million from anxiety disorders [
1]. Depression is ranked as the leading cause of disability worldwide [
2]. Every 40 s, someone loses his or her life due to depression, which has caused a serious public health care burden. Mental health disorders are not just “mood disorders”, as they are commonly known, but are caused by a complex interaction of genetic, neuro-biomechanical, endocrine, and social factors and are characterized by prolonged depressed mood, sleep disturbances, feelings of self-ignorance, fatigue, and low energy, and in severe cases, even self-harm or suicidal thoughts.
Decreased physical activity [
3] and sleep disturbances [
4] are two important factors in the onset of mental health disorders, but they are not the only ones. Daily behavioral rhythms (e.g., motor activity) and daily physiological rhythms (e.g., sleep and appetite) are also often disrupted during depression [
5,
6]. High-energy food consumption resulting from the unhealthy eating habits of the Western lifestyle is associated with poor mental health [
7]. However, consumption of foods such as fruits, vegetables, unsaturated fats, and foods rich in vitamin D was significantly and positively associated with mental health [
7,
8]. Poor health lifestyles such as low physical activity, poor diet, smoking, alcohol, and substance abuse are often found in patients with serious mental illness [
9]. That mentally passive sedentary behavior (for example, watching TV) [
10] also contributes to the increase of the symptoms. In a study of Chinese adolescents, time spent online or playing video games, as well as heavy study or homework outside of school, negatively impacted adolescents’ self-rated health and psychological well-being. Additionally, screen time has the greatest impact on mental health [
11]. Although there are numerous ways to prevent and treat mental health disorders (e.g., medication, interpersonal psychotherapy, etc.) as economic and medical technology develops, 75% of patients in low- and middle-income areas still do not receive treatment [
12].
Several studies have shown physical activity to be effective in reducing the incidence of depression and anxiety, and its treatment guidelines recommend exercise as a treatment strategy for managing depressive symptoms [
13]. The effect of physical activity on mental health improvement has been found to be significant in various populations. In a study of Brazilian adolescents, emotional well-being was positively correlated with physical activity and negatively correlated with screen time [
14]. Studies have found that physical activity can improve depressive symptoms in older adults [
15]. After a minimum of four weeks of physical activity intervention, older adults showed improvements in scores on the Anxiety State, Trait Anxiety, and Anxiety Self-Assessment scales [
16]. Cai et al. [
17] found that physical activity during pregnancy reduced the prevalence and severity of preconception depression and anxiety. A study by Goodwind et al. shows that people without daily physical activity have a higher risk of depression than those who are physically active [
18]. In addition, physical activity is considered a cost-effective intervention, both for the prevention and control of the condition [
19] or as an adjunct to treatment for mental health disorders [
20]. Suicide rates among patients can be reduced through exercise [
21], and this is even more evident in critically ill patients. In addition, exercise was associated with a significant reduction in OCD [
22]. The factors that improve mental health disorders with exercise are related to the hormones secreted by the body during exercise. Both dopamine, secreted in large amounts at the beginning of exercise [
15], and endocannabinoids, secreted in large amounts during sustained exercise, can reduce anxiety and depression after exercise and make people feel relaxed and happy.
Circadian rhythms are approximately 24 h endogenous oscillations that influence and regulate the chronology of almost all human behavior and physiology [
23]. A large body of research suggests that circadian rhythm disturbances may be a causal factor in some depressions (major depression, bipolar disorder, etc.) [
24,
25]. Eveningness is a common circadian phenotype in depression, with some studies reporting an increased risk of suicidal behaviors and more severe depressive symptoms among evening types than among morning types [
26,
27,
28]. Early morning people have lower suicide rates than night people, which may be related to a causal relationship between early morning and improved mental health [
29]. Although strong associations with depression [
30], obsessive compulsive disorder (OCD) [
31], and somatization [
32] have been found in circadian rhythm sleep-wake disorder phase disorders, not too many studies were found on the chronological type of circadian rhythm differences with other psychological disorders other than depression.
The SCL-90 score is divided into a total score and a factor score. A total score of more than 160 or a factor score of more than two needs to be considered a positive screening, and a positive score indicates a possible mental health problem, and a higher score indicates a higher degree of mental health problem. Additionally, the nine factors of the scale represent the distribution characteristics of individual symptoms. In previous studies, most studies have focused on the effects of physical activity and sleep on somatization, obsessive-compulsive depression, anxiety, and other symptoms, and few studies have addressed interpersonal sensitivity, hostility, phobia, paranoia, and psychotic symptoms. The present study examines the effects of physical activity and circadian rhythm differences on OCD, interpersonal sensitivity, depression, anxiety, hostility, phobia, paranoia, and psychoticism through a cross-sectional study.
4. Discussion
There is increasing interest in research on the relationship between exercise and mental health, but current research has focused more on depression and anxiety symptoms, with only a small number of studies on obsessive-compulsive disorder, somatization, interpersonal sensitivity, hostility, terror, and paranoia. The present article is the first study to combine physical activity and circadian rhythm differences to produce effects on somatization, obsessive-compulsive disorder, interpersonal sensitivity, depression, anxiety, hostility, terror, paranoia, and neuroplasticity, but the results of physical activity and circadian rhythm differences on psychopathic patients were not statistically significant.
4.1. Physical Activity
Scholars have found that for every standard deviation increase in physical activity level, symptoms of somatization disorder decrease by 10.7% [
38]. The results of this study were the same as theirs. However, this article also found that men were more likely to have somatization symptoms than women. Regarding obsessive-compulsive disorder, the results of the current study showed that moderate and high-intensity physical activity possessed lower obsessive-compulsive symptoms among college students, with women having more pronounced obsessive-compulsive symptoms than men. Although no effect of differences in physical activity levels on obsessive-compulsive symptoms was found, there are arguments for the improvement of OCD with different intensities of exercise. Two studies by Abrantes et al. showed that aerobic exercise lasting at least 20 min and moderate-intensity continuous training up to at least 150 min per week significantly reduced symptoms of anxiety, depression, and obsessive-compulsive disorder [
39,
40]. Interpersonal sensitivity was only found in a Moroccan study of factors associated with physical activity and mental health during the closed quarantine of the COVID-19 pandemic, which showed that low-intensity recreational exercise did not bring about significant changes in interpersonal relationships, while the higher the intensity of exercise, the more pronounced the improvement in symptoms [
41]. The results of the current study showed that for each standard deviation increase in physical activity, the phenomenon of interpersonal sensitivity decreased by 1.94 times. In addition, college students with low physical activity levels were more likely to experience depression and anxiety symptoms relative to moderate and high-intensity students, a result identical to that of the previous authors. Ghrouz et al. found that moderate and high-intensity physical activity levels were significantly and negatively associated with depression and anxiety [
42]. In terms of gender, the results of the study by Grasdalsmoen et al. showed that men were more prone to depressive tendencies than women at low intensity levels [
43]. In contrast, this paper found that women had a higher risk of developing depression than men at low-intensity activity levels. In addition, there is less research on the effects of differences in physical activity levels on hostility, phobia, and paranoia symptoms. Although some studies suggest that the idea that greater hostility is associated with less physical activity in populations with low social support is the same as the results of the current study, further research is needed on the relationship between physical activity and hostility. Aerobic exercise and physical activity showed some improvement in symptoms of phobia and paranoia, but more detail was not given on the intensity and duration of exercise. It is necessary to conduct an experimental study to explore the positive effects of physical activity on hostility, phobia, and paranoia symptoms.
4.2. Circadian Rhythm Differences
In a review of sleep chronotype, circadian rhythms, and mood, Bauducco et al. found that regardless of study design and measurement type, people with late sleep patterns had a higher risk of depression [
44]. This view is the same as the results of the present study. Regarding the effect of circadian rhythm differences and anxiety symptoms in adolescents, the findings of related researchers are also consistent with this paper in that late sleep chronotype students are more likely to be anxious and have poorer sleep quality than early morning chronotype students [
45]. In patients hospitalized with OCD, it was found that altering the sleep-wake phase delay by controlling the time of lights out significantly improved obsessive-compulsive symptoms, more so in severe patients [
46]. In conducting the literature review and collection, no studies have been found on the correlation between circadian rhythm differences and symptoms of interpersonal sensitivity, hostility, fear, or paranoia. However, the results of the present study showed that for each standard deviation decrease in circadian rhythm variance score, there was a corresponding increase in interpersonal sensitivity, hostility, phobia, and paranoia.
4.3. Limitations
- I.
The data was collected through questionnaires, which came from the respondents’ subjective feelings, which may have certain biases;
- II.
The sample size is not large enough, covering a relatively small area of colleges and universities, and the data will be continuously tracked and improved in the future to continue the study.
4.4. Future Research Directions
Future research directions should use controlled experimental approaches to condition interventions corresponding to physical activity and circadian rhythm differences to explore what beneficial effects would occur in people with mental health problems when both are equally effective.