The traditions of higher medical education in the Russian Federation have always been closely connected with the immersion of students in a professional environment [1]. For this purpose, medical students are involved in the work, and it has become the usual practice. Many medical students in senior courses have a part-time job (half-time or quarter-time) as junior or secondary medical personnel, which is explained by a number of reasons: the desire of students to gain financial independence, the opportunity to get additional points for admission to residency, the shortage of medical workers (in particular among the secondary medical staff), the need for students to develop professionally and gain practical experience. Thus, the development of practical skills related to the activities of secondary medical and pharmaceutical personnel will be useful in the practical activities of any doctor and pharmacist, especially when working in rural areas, in military healthcare, or in remote regions, since there are often not enough secondary medical personnel [2].

The publication of the order of the Ministry of Health of Russia dated March 19, 2012. No. 239n “On approval of the procedure regulations for admission of persons who have not completed the basic educational programs of higher medical or higher pharmaceutical education, as well as persons with higher medical or higher pharmaceutical education, to carry out medical or pharmaceutical activities in the positions of secondary medical or secondary pharmaceutical personnel” made it possible to solve two main tasks at once: to fill the deficit of secondary medical staff and to give the real practice for future doctors while they finish their basic training [3].

It should be taken into account that students suffer from a mental load, which is higher than the one of full-time medical staff, since, in addition to work, they are to visit their main place of study. Thus, a study by Średniawa et al. (2019) in Krakow showed that 23% of students experienced stress almost every day [4]. According to the data of Chowdhury et al. (2021) from Noakhali University of Science and Technology, the poor sleep quality of students affects their physical and mental health, also causing mental problems such as anxiety and depression [5]. This is also evidenced by the data of Manzar et al. (2021) published in a study at Majma University, Al Majma, Saudi Arabia [6].

It should be borne in mind that the work of nursing staff usually takes place on a shift basis: from 8 AM to 4 PM (“day”), from 4 PM to 8 AM (“night”). During shift work, biological rhythms are out of sync, which entails negative consequences, including changes in behavior and daytime activity, sleep disorders, and changes in hormonal regulation and metabolism [7]. Alqudah et al. (2019) believe that sleep deprivation can lead to hallucinations and delusional behavior and indirectly predispose to multiple systemic diseases, which together can affect a person's quality of life [8]. At the same time, researchers from Ethiopia (2020) [9] concluded that Ethiopian college students had a high prevalence of insomnia, which is associated with both anxiety and poor sleep hygiene.

All in all, to the greatest extent, shift work is associated with an increased risk of cardiovascular diseases, obesity, and type 2 diabetes. A statistically significant correlation between sleep disorders and BMI was proven as well [10]. Diseases of the digestive tract associated with shift work vary from dyspepsia, gastritis, and peptic ulcer to heartburn, constipation, flatulence, and appetite disorders. The development of pathology is facilitated by the desynchronization of circadian rhythms of the gastrointestinal tract, which control gastric secretion, enzyme activity, and intestinal peristalsis. Shift work increases the likelihood of developing cancer. The pathogenetic mechanism is the inhibition of melatonin synthesis by artificial light during night working hours, which increases the level of estrogens and promotes the growth of hormone-mediated tumors.

Shift work may also affect mental health. It has been proven that it is associated with higher levels of anxiety and depression [11]. Several conducted studies revealed a correlation between suicidal behavior and insomnia [12][13]. The dysregulation of the melatonergic system due to forced activity at night is pathogenetically associated with the formation of alcohol use disorders [14]. In addition, the relationship between insomnia and academic performance was proven. According to the results of binary logistic regression analysis of the relationship between approximate insomnia disorder and academic performance/underachievement, insomnia was significantly associated with higher chances of exam failing [15].

The authors of this study found no scientific studies on the problem of mental health disorders and sleep disorders in students working and not working as secondary medical personnel. In this regard, the comparison of mental state and quality of sleep in these groups of students is considered to be relevant.

The purpose of the study is to compare the severity of the relationship between mental state and insomnia in medical students working and not working as secondary medical personnel.

This study was randomized. The research methods were sociological, psychometric, and statistical. The study was conducted on the basis of Bashkir State Medical University (BSMU) during the period from February to April 2022. All the students gave their voluntary informed consent. The data was collected by means of using a Google form.

Therefore, 185 participants were included in the study (7 people were subsequently excluded due to defects when filling out the questionnaire form). The 1st group included 172 people (70 men (41%), 102 women (59%), the 2nd group included 66 students who did not combine university studies and work activities (11 men (16.7%), 55 women (83.3%)). The average age of participants in both groups was 21–23 years.

The SCL-90-R technique (Symptom Check List-90-Revised, Derogatis, Rickels, Rock, 1976) was used in order to assess the mental state [16]. The Insomnia Severity Index (ISI, Insomnia Severity Index, ISI, Bastien et al., 2001, Savard et al., 2005) was used in order to assess insomnia disorders [17]. In addition, the Pittsburgh Sleep Quality Index (PSQI) was used as well in order to assess sleep quality [18].

Microsoft Excel and STATISTICA 10 software packages were used for the statistical processing of the data obtained about the subjects. The Shapiro-Wilk criterion was used in order to assess the normality of the distribution of quantitative variables. In connection with the distribution of variables other than normal, methods of nonparametric statistics were used. In order to establish the relationship between the studied phenomena, the Spearman correlation coefficient was used. In order to compare the studied groups, the Mann-Whitney U-test was applied.

The prevalence of insomnia in the 1st group was 45.9%, in the 2nd group — 48.5%. While comparing groups by means of using the Mann-Whitney U-test, the authors of the study found that students who did not work as secondary medical personnel had higher scores of the SLR-90-R questionnaire: “Obsession” (p=0.007), “Sensitivity” (p=0.0002), “Depression” (p=0.0047), “Anxiety” (p=0.015), “Phobia” (p=0.012). A similar pattern was observed in second-order indices. The overall severity index of symptoms in the 2nd group was higher (p=0.002), as was the symptomatic distress syndrome (p=0.015). In this case, the insomnia was at the same level as in the 1st group (p=0.899). Similar results were obtained while conducting a correlation analysis by means of using Spearman's rank correlation method between the severity of mental state changes in the 1st group (according to the results of the SCL-90-R scale) and the severity of insomnia disorders. Therefore, the statistically significant correlations were obtained as follows: in the case of more pronounced insomnia, more pronounced results for such subscales as “Somatization” (R=0.5; p=0.000), “Obsession” (R=0.5; p=0.000), “Sensitivity” (R=0.4; p=0.000), “Depression” (R=0.5; p=0.000), “Anxiety” (R=0.4; p=0.000), “Hostility” (R=0.4; p=0.000), “Phobias” (R=0.4; p=0.000001), “Psychoticism” (R=0.4; p=0.000), “Paranoia” (R=0.3; p=0.0005).

In the 1st group, students with insomnia had a higher overall symptom severity index (GST, which reflects the depth of the disorder and remains an indicator of the current state) than insomnia-free students. The index of available symptomatic distress (PTSD) was also higher. This indicator reflects the presence of symptomatic manifestations of a negative form of stress.

The process of sleep is closely related to the hypothalamic-pituitary-adrenal system. In the first stages of sleep, the effect of this system on the body is suppressed, but within the second half of sleep, its activity begins to increase.

Stress affects the hypothalamic-pituitary-adrenal and sympathoadrenal systems, activating them. This leads to the release of adrenocorticotropic hormone (ACTH), cortisol, and catecholamines. The excessive release of ACTH leads to early awakenings, sleep disorders, and insomnia. In turn, with insomnia, the parts of the brain responsible for emotions and areas of the prefrontal cortex regulating cognitive function are involved in the excessive process of arousal. Excessive cortisol release negatively affects the hippocampus, impairing memory. All these processes lead to behavioral and cognitive maladaptation [19]. The result is the deterioration of mental health.

The higher rates of mental state disorders in the 2nd group of students suggest that, due to these personal characteristics, non-working students have less adaptive potential and adapt worse to changing environmental circumstances, which is the reason for their choice not to combine academic activities and work. Poor sleep quality may be associated with an increased level of mental stress [20], which in turn is associated with certain personality traits of students [21].

The results of this study confirm the data of foreign researchers who record associations between sleep disorders and mental health disorders. However, there is not any sufficient reason to believe that sleep disorders among working students are associated with their work and study schedules, since non-working students had worse indicators. In addition, the authors of this article did not take into account the hours actually spent by students on training and work and the intensity of these activities in each individual case, which requires an additional, more in-depth study.

The results of this study make it possible to say that a relationship between the mental state and insomniac disorders in medical students (both who are working as secondary medical personnel and who are not working) has been established. The authors of this study suggest that students who do not work as nurses have low adaptive abilities, as a result of which their mental state is accompanied by more pronounced insomniac disorders. These obtained results may be used in the formation of preventive measures in order to preserve the mental health of students, timely informing them about the possible risks of additional loads, and also be the basis for reviewing medical students’ curricula.