1. Analysis of rhythm characteristics and its sociological value under the stress of COVID- 19 epidemic
Biological “clock” and its rhythms are a kind of prediction and early warning mechanism selected by the environment in the process of evolution over the years. Species which can grasp the law of environmental changes and foresee what happens have the advantages of survival and reproduction.11,19,20 A study published in Lancet Psychiatry showed that the early identification and intervention of rhythm disruption have important clinical significance.10 Previous studies have shown that rhythm disruption is associated with poor mental health problems, such as depression, anxiety, low happiness and strong loneliness.10,14-17
The present study found that the rhythm disruption of life, work and entertainment in females were worse than that in males. This gender difference may be attributed to the fact that oestrogen would affect the balance of hypothalamus-pituitary-adrenal axis (HPA axis) under COVID-19 epidemic stress, making females are more sensitive to HPA axis than males.21-22 Additionally, menopausal women's circadian and endocrine disorders are more likely to lead to rhythm disruption.
In this study, a significant difference was found among people with different ages in the rhythm scale. This age-related difference may be explained , First, it is known that people aged 26-40 years old are the main force of the society, and actively participate in the activities of various industries, which promotes the consumptions, cultural creativity and economic development. However, they had to stay at home or fight against the epidemic due to the sudden outbreak of COVID-19 epidemic.23-24. Second, people under 18 and those aged 18-25 years old participating in the present study were mainly students. During the COVID-19 epidemic, they participated regularly in home network courses and distance educations organized by education supervisors.25 So, these groups of people remained their regular life, study rhythms during the epidemic. Third, the phenomenon that people aged 18-25 and 26-40 years old maintained their regular entertainment rhythm, such as home physical exercise, literary and artistic activities, advocated by the responsible cultural and sports executives. Fourth, it has been shown that people with poor health status or older than 61 years old have more basic diseases, weaker immune function, and low ability to fight pathogens or adapt to rhythm replacement.26-27 Thus, they did not dare to come out to participate in outdoor sports during the epidemic, and thus their the life, work and entertainment rhythms were all affected by the epidemic.
The present study found that the people with low educational levels or low annual income were most like to have irregular life and work rhythms. This may be explained by the assumption that these people have weak competitiveness in the job market and are currently waiting for the resumption of work and production. Moreover, they have not yet adapted to the new business models. Interestingly, the people with master’s degree or above were most like to have irregular entertainment rhythm. This might be resulted from the fact that these intelligent people mainly concentrated on medical care, education, scientific research, artificial intelligence engineering and so on., and thus, they had little leisure time during the COVID-19 epidemic.28 In addition,The most irregular in the divorced or widowed group might be related to the disintegration of the family, loose family relations, economic problems, and the problem of raising children as a single parent.29 Especially, the isolation during COVID-19 epidemic may have aggravated the fear for the unknown future, loneliness, helplessness, or irregular eating and drinking.
The life and work rhythms of nurses were the most irregular among different occupations. The main reasons were assumed as follows. First was the particularity of nursing work.30-31 Nursing staff reserves are relatively insufficient and multiple shifts work became more frequently during the COVID-19 epidemic. Second, the risk and relative closure of the work environment, indoor equipment and noisy environment, and closeness to patients all increased the tension and anxiety.Third, nurses worked at high intensity and high pressure. Nurses needed to deal with patients' emergencies immediately, especially for critically ill patients who needed a ventilator, tracheotomy, or extracorporeal membrane oxygenation (ECMO). Nurses not only did therapeutic nursing, but also did some life care, disinfection and isolation.
2. Analysis of psychological problems under the stress of COVID-19 epidemic.
The present study found that there were significant differences in psychological disorders among in people with different backgrounds. First, the HPA axis was more responsive to stress in women than in men, as described earlier.21,22 Second, people with low education levels were not competitive in the work market, and thus more likely to be affected by the epidemic and face the grim employment situation. Moreover, they did not have sufficient judgement while facing various, overloaded and timeless information on COVID-19 epidemic, and easily felt depressive and anxious. Third, people aged 26 to 40 years, the backbone of the society and families, especially those fighting against the epidemic resulted in psychological impact. The depression and anxiety existed with a high prevalence in the group of medical staff, especially in nurses. The reasons might be the follows.30-31 First, COVID-19 is a new infectious disease with a sudden epidemic, and thus medical staff had no or little knowledge on its route of transmission, prevention and treatment, and thus worried about the infected risk. Second, medical staff were difficult to balance between work and family, and especially after working in the isolation ward, they had to be separated themselves from the family for a long time. Third, when the medical staff encountered the new confirmed or suspected cases every day, witnessing patients in great pain but failing to save their lives despite their best efforts, they would feel frustrated and guilty. Fourth, the mental health disorders in nurses were the most serious among the various occupations, this may be related to their special occupation, working environment, high-risk and arduous tasks during COVID-19 epidemic, as mentioned earlier.
3. Analysis of association between the disrupted rhythms and psychological problem
A previous study observed an association of disrupted circadian rhythmicity with mood disorders by wearing a wrist-worn accelerometer for 7 days, and found that circadian disruption could increase the risk of depression, bipolar disorder; compared with people who worked normally, the prevalence rate of mood disorders was 6-10% higher in people with circadian disorders.10 However, the present study found that the prevalence rates of depression and anxiety in high-score group with rhythm disruption of life-work increased by 34.50%, and 47.16%, respectively, suggesting that the rhythm disruption under the stress of the COVID-19 epidemic had triggered a higher and more risk of mental health problems.
Our research further found that the scores of life and work rhythms were positively correlated with SDS and SAS scores. This association was theoretically based on the following aspects. First, the hypothesis of "social timing factor theory" holds that stress is a regulating factor of biological clock, which leads to various adverse mental health.32 Second, the "knockout monkey" model had circadian rhythm disruption with analogous schizophrenia symptom after knocking out the core rhythm gene of BMAL1 .33Third, it has been reported that the disrupted rhythm of suprachiasmatic nucleus leads to helplessness and despair, and increases depression and anxiety-related behaviourss.34 Fourth, the function of HPA axis is also regulated by the biological clock.35 Therefore, we speculate that if the treatment of depression and anxiety disorders is organically combined with the regulation of the biological clock to restore the biological rhythms, then the efficacy of antidepressants would be significantly improved.
In general, entertainments, such as regular physical and cultural activities could relieve adverse emotion such anxiety and depression.36-37 However, in this study, for the special nurse group with rhythms disruption of life and work , it seems difficult to improve anxiety and depression through regular entertainment under stress of COVID-19 epidemic. Thus, it is necessary to further evaluate rhythm disruption and mental health problems of the target population, identify the possible signs of group psychological crisis, and incorporate psychological crisis intervention with adjustment of disrupted rhythms of life, work and entertainment timely for the high-risk groups to avoid extreme events, such as self-injury or even suicide.
4. Synchronized intervention strategy for rhythm disruption and psychological problems.
Currently, extensive attention has been paid to the biological clock in the field of psychiatry and psychology due to its importance.6,10-12,38,39 We hope that future research on optimizing the functions of the biological clock can develop a new area of "rhythmic medicine". If the circadian rhythm could be more effectively integrated with the warning, diagnosis and treatment of psychosomatic diseases, then, mental health might be improved, psychosomatic diseases prevented, and the therapeutic efficacy maximized. Therefore, based on the findings of the present study, we recommend reversing the disruption of life, work and entertainment rhythms, cooperating with classical psychological therapy, and intervening the psychological impact caused by COVID-19 epidemic.
Presently, health-care workers are the most valuable resource of each country, their safety must be ensured. For medical groups, especially nurses with the rhythm disruption, depression and anxiety, we would recommend the following the interventions. First, the adjustment of the daily rhythm starts from the virtuous circle such as the habit of going to bed early and getting up early, exercising appropriately, changing your posture, basking in the sun and listening to the music. Second, drugs with adjusting the biological clock should be considered for sleep disorders caused by nurses’ shift system, when necessary.40,41 Third, the rhythm of work should be changed properly such as adjusting the working time, and transferring work from the high stress job to the low stress job. Fourth, the eating patterns and food should be adjusted.Previous studies have shown that regular eating and various metabolites promote the periodic colonization of the intestinal bacteria on the mucosal surface, and then alleviate various adverse mental problems through the intestinal flora-gut-brain axis42,43. Fifth, as nurses had high vulnerability to COVID-19, adequate provision of personal protective equipment is necessary and hospital-specific protocols should be established to reduce the risk of nurses' infection in the interactions with patients.44-45