The Associations Between Chronotype and Mental Health in Nursing Students

Every day, the world changes on a scheduled basis, approximately every 24 h. As a result, living things have had to develop internal systems that prepare them for this change. These systems have allowed different animal species to adapt to the time of daylight or darkness in their environment through rhythms of activity aligned with the daily cycle of light and dark [1,2,3]. In this way, there are biological variables that show a defined periodicity with a cycle length of 24 h. These oscillations of variables are called circadian rhythms and include physiological, psychological, and behavioural variables [3]. Psychological variables include mood, alertness, sleepiness, and task performance [4,5]. For humans, Horne and Östberg [6] identified this variability in sleep pattern (morningness/eveningness preferences), referring to early risers as “morning types” and late risers as “evening types”. These individual differences affecting the timing of sleep and activity during a 24 h day are known as chronotypes [7]. It is an intrinsic characteristic of each human being, which can be classified according to the circadian rhythmic expression of sleep and activity [8]. Studies have shown that the evening chronotype can be a risk factor for depressive disorders and substance use disorders, while the morning chronotype is a protective factor [4,9,10,11].

Some circadian rhythms are misaligned in the university environment relative to the non-university population [12]. This may be due to different social habits of student life: irregular work/rest schedules, preoccupation with exams, relationships with classmates, place of residence/independent living, late nights due to late-night internet surfing, partying, work, alcohol and other drug use and/or abuse, time management, self-regulation, and living with peers [13,14,15]. This may be a risk factor for various health problems, including sleep problems and anxiety [16].

Registered nurses suffer from depression at almost twice the rate of individuals in other professions [17]. On the other hand, college students face challenges related to independent living and academic difficulties. This predisposes them to depression, anxiety and stress, which are standard [18,19]. Many studies on depression among nurses have been mainly related to shift work, which is the primary mode of work for nurses [20,21]. Many health professionals, such as nurses, work at night and must sleep during the day. These work shifts affect their sleep quality and sleep quantity and misalign in the individual’s circadian rhythm [22]. Sleep quality is fundamental to health, and its cumulative effects have been associated with serious health problems. These problems include diabetes, cardiovascular disease, obesity, depression, anxiety, myocardial infarction, and stroke [22,23]. Health problems of nurses and nursing students also affect patients and organisations. Nurses are key to patient safety, as they are directly responsible for patient care [20]. In this regard, it has been shown that depression in nurses can affect both professional performance and lead to errors and negligence [24,25]. Furthermore, depression is linked to increases in work absenteeism, short-term disability, and decreased productivity [17]. The leading causes of drug preparation and administration errors have been shown to include stress, fatigue, increased workload, night shifts, nurse staffing ratios, and workflow interruptions [20].

Prevention is key to avoiding mental health problems. In the case of nurses and nursing students, due to their vulnerability to specific mental health problems such as depression and its impact on patient safety, preventive measures are of particular interest. These measures could be initiated during their university training since university students may undertake shift work experience in hospitals that could hurt their health. Because evening type has been linked to an increased risk of depression, preventive measures could include an assessment of individual chronotype. In this regard, it is helpful to study the chronotype preferences of nurses and nursing students to promote self-care and implement appropriate measures to ensure patient safety. In this way, by preventing mental health problems in nurses, we will also be preventing health problems in the patients under their care and ensuring better functioning of the hospitals and organisations where they work, with lower absenteeism and improved productivity. In addition, implementing self-care behaviours to prevent mental health problems in nursing students can benefit them as they transition from undergraduate to graduate nursing roles [26].

Studies have been conducted on the influence of chronotype on university students’ academic performance and learning motivation outcomes [27,28]. The impact of chronotype on social jet lag and quality of life has also been examined [29]. However, regarding university students, there are few studies linking chronotype to mental health issues such as depression, anxiety and stress. A study involving Chinese medical students revealed a significant association between chronotype and depressive symptoms [30]. Chang et al. [31] found that an evening chronotype among medical students posed a risk factor for anxiety and depression. Another study involving college students indicated that being an early riser might serve as a protective factor, not only against depression but also against suicide [32]. As far as studies analysing the relationship between chronotype and mental health in undergraduate nursing students in Spain are concerned, none exist in the scientific literature. Thus, to our knowledge, this is the first study to analyse the relationship between chronotype and depression, anxiety, and stress in university nursing students in Spain. On the other hand, in addition to analysing the relationship between chronotype and mental health in nursing students, it also studies for the first time the role played by sociodemographic factors in this association.

To our knowledge, this is the first study conducted to examine the association between chronotype and mental health problems in Spanish university nursing students. Our results show statistically significant associations between the total Goldberg scale score and the depression and anxiety subscales, with higher scores observed in the group of students characterised by the evening-type chronotype. Similarly, a study performed in Chinese medical students [30] reported a positive correlation between evening chronotype and depressive symptoms. Likewise, the study by Park et al. [32] conducted with Korean college students showed that depressive symptoms and suicidality were statistically higher in evening-type chronotype college students than in morning-type college students. These results could be related not only to sleep pattern but also to other variables such as sleep duration or sleep quality. Previous research has shown that, compared to morning people, individuals with a nocturnal chronotype have a longer sleep latency [43] and a shorter sleep duration [10,44]. In addition, studies such as Giannotti et al., 2002, have shown that individuals with nocturnal chronotype have an irregular sleep–wake schedule, poor sleep quality and, greater daytime sleepiness than morning types [45].

Greater emotional intelligence could help regulate mood regardless of chronotype (morning or evening). People with lower emotional intelligence, especially evening types, may be more prone to experiencing variations in their mood throughout the day, which could partly explain the observed association [46]. According to the results of the regression analysis in this study, some socio-demographic variables, such as gender or other lifestyle-related variables, such as daily consumption of stimulant drinks (coffee, cola or tea), were found to be predictors of mental health. Thus, we found statistically significant correlations of the Goldberg depression subscale with both gender and daily consumption of stimulant drinks. In our study, women had more depressive symptoms than men, and people who consumed stimulant drinks daily had fewer depressive symptoms than those who did not consume these substances. Our results are supported by other studies of university students, which have shown that depressive symptoms were higher among women than among men [47,48]. On the other hand, the short-term effects of caffeine consumption on mental health have been documented and include improved mood and alertness [49,50,51]. Previous studies in high school students [52] found that the incidence of depression decreased as the level of caffeine consumption increased. Similarly, caffeine consumption was associated with a lower risk of depression compared to no consumption [21].

Regarding the anxiety subscale score, the results of our study showed significant differences in the three chronotype categories, with higher scores in the intermediate and evening chronotypes. Previous studies have shown results that go in the same direction. Luz et al. [53] conducted a study with Brazilian university health science students and found that morning chronotype students showed lower anxiety levels (state and trait), and the evening chronotype in University Brazilian students was associated with higher anxiety states than the morning type [54].

Regarding the self-perceived stress scale, the analysis of our study shows significant differences between the total score of the scale and the three chronotype categories, with students from the intermediate and evening chronotypes obtaining the highest scores of stress. In a previous study conducted with students from the psychology field [55], a tendency for higher stress levels was reported for the students belonging to the evening chronotype. To our knowledge, the relationship between chronotype and self-perceived stress has not been studied in undergraduate nursing students. This relationship was studied in a recent study conducted in professional nurses, and the results were like those observed in nursing students in the present study; as a matter of fact, the perceived stress scores of the evening chronotype nurses were higher than those of the morning type [56]. According to the results of the regression analysis in this study, gender was found to be a predictor of stress. Thus, women showed higher stress values than men. In general, gender studies in the scientific literature have found that women have higher stress levels than men [57,58], as we have found in our study. Similarly, a recent study of nursing students found statistically significant gender differences in both clinical and academic settings, with women having significantly higher levels of total perceived stress than men [59]. When analysing the effects size in multivariate analyses in order to measure the strength of the relationship between the predictors and the outcome variables, e.g., psychological variables, indicating how much variance of the outcome variable is explained by the model, we found that the most strong were for anxiety symptoms (R squared 0.309) and for depressive symptoms (R squared 0.287), suggesting that around 28–30% of the variance can be explained by the independent variables.

Although most of the students in our study had an intermediate chronotype, the second most frequent chronotype turned out to be the evening chronotype. While chronotype can be modified with light exposure [60], the tendency toward the evening chronotype could be due to environmental demands [61], particularly social demands, which can generate a mismatch known as social jet lag [62]. Social jet lag negatively affects academic performance, particularly in women, by impacting various cognitive abilities and lowering their grade point average [63]. Social jet lag refers to the circadian mismatch that occurs when people shift their sleep schedules from weekdays to weekends [64]. Thus, people with social jet lag tend to sleep too little during the workweek and sleep too much on weekends [65]. Most people suffer from social jet lag throughout their school and working lives, but according to Roenneberg et al. [60], this phenomenon is greatest around the age of 20. This is because the chronotype is, on average, later in adolescence than at any other age. This statement would justify the tendency towards the evening chronotype in our study, since the mean age of our sample was 20.60 years (±2.56). Furthermore, in the case of university students, it could also be influenced by academic activity beginning early in the morning. This schedule would cause students with later chronotypes to have higher perceived stress [66], potentially due to a greater decrease in mood and lower alertness experienced in the morning [67]. This could be especially influential in the case of nursing students who must perform internships in clinical settings at early stages, and in those who must demonstrate high performance in the care of real patients, who can face serious health problems. In our study, no significant differences were observed between chronotype type and other sociodemographic variables such as age, gender, marital status, having children and place of residence during the academic year, smoking, consumption of alcoholic beverages or stimulants, BMI, chronic diseases, or daily consumption of psychotropic drugs. There were also no significant differences between physical activity and chronotype. In this study, a high prevalence of mental health problems (46.4.3% depression, 45.3% anxiety, and 79.6% stress) was found in undergraduate nursing students. In recent years, an increase in the rates of college students experiencing symptoms of depression and anxiety has been observed [68,69]. In a study based on the World Health Organization (WHO) global surveys of university student mental health, involving universities in eight countries (Australia, Belgium, Germany, Mexico, Northern Ireland, South Africa, Spain, United States), approximately 31% of university students experienced some mental health disorder over the course of the past year [70]. Of all mental health problems analysed, the most common was major depressive disorder (21.2%), followed by generalised anxiety disorder. Regarding health sciences students, some studies suggest that the prevalence of mental disorders is higher in students from health sciences compared to other areas of studies [71]. A multicentre study carried out in 43 medical schools in Spain reported an overall prevalence of depression of 41% and of anxiety 25% [71]. In our study, the prevalences of depression and anxiety were even higher, being a little bit higher, e.g., 46 and 45% approx., respectively. This may be because the stressors faced by nursing students differ from those of other disciplines, due in part to the fact that nursing curricula simultaneously involve studying in didactic and clinical settings [72]. Although undergraduate nursing education equips students with the knowledge and skills for practice, facing real situations of patient suffering may increase the risk of students experiencing stress, anxiety, or depression [73]. On the other hand, most participants in our study were female (86.5%) and, therefore, this high prevalence of depressive symptomatology could be because depression is usually higher in women than in men [74,75]. Furthermore, although gender did not show significant differences with the anxiety subscale in our study, a tendency towards depression in favour of women was observed (p = 0.05). Regarding age, the students in our study with higher anxiety symptoms had a significantly older mean age (20.84 (±2.46) years) than students with lower scores (p = 0.039). This increase in anxiety in older students could be due to being upperclassmen performing special service placements and facing other stressors. In this direction, Yi et al. [76] demonstrated in their study that undergraduate nursing students were more prone to anxiety during the last period of their clinical internship. In addition, these students presented specific sources of anxiety such as career decision making, job search, graduation and licensure examination [77,78,79]. In addition, we detected that the students with a greater burden of symptoms of anxiety and/or depression reported a worse self-perception of their health status according to the findings of another study conducted among Bangladeshi university students [80]. Regarding self-perceived stress, 79.6% of the participants in our study reported stress symptoms. On the other hand, the results of the multivariate regression analysis showed that the chronotype was a variable that predicted self-perceived stress. Thus, there was a statistically significant correlation between stress and evening vs. morning chronotype, with participants with evening chronotype having higher levels of stress. Stress has been identified as a predictor of anxiety among nursing students [78]. High levels of stress could have serious mental health consequences, such as increased risk of anxiety and depression [81,82].

The present study adds new evidence for the association between chronotype and depressive and anxiety symptoms, with students exhibiting an evening-type chronotype displaying a higher burden of these symptoms. This represents a potential subgroup of patients who could benefit from interventions aimed at improving their mental health, as demonstrated by recent studies in various countries indicating that the quality of mental health among young people or young adults is quite low [83]. However, some limitations have been identified in the study that need to be considered when designing future research in this area. Although the majority of our study population was female, it is a representative sample of the population studied. Nursing is a feminised profession, both in terms of the number of university students and the number of registered professionals. According to a recent Ministry report, in Spain, approximately 85.5% of registered nurses are women [84]. However, we cannot generalise our results to university students from other degrees that are not predominantly female, and this is a limitation. Because the information on anxiety, depression, and stress symptomatology was obtained through self-reported scales, we cannot provide a clinical diagnosis to explain the associations observed. Additionally, the sample was a convenience sample, as students opted to participate in the survey voluntarily; thus, we cannot generalise these findings to the entire population. Moreover, in these circumstances, people with mental health problems in the sample studied might have been more likely to participate. This circumstance could have contributed to a bias in the responses. However, the fact that the survey was anonymous may have encouraged participation from students with known mental health problems. Supporting this assumption, the rates of depressive and anxiety symptoms we detected were like those published by other authors. Despite these limitations, our study incorporates validated scales commonly used in clinical settings and research.

The results of the current study are significant, as they indicate that the morning chronotype serves as a protective factor against mental health issues among university nursing students. Conversely, the evening chronotype is a risk factor, particularly affecting women’s mood. These findings underscore the importance of evaluating chronotype in nursing students and have public health implications, given that chronotype (and gender, in the case of depression) is closely linked to the symptomatology of depression, anxiety, and stress. Although gender and chronotype are non-modifiable individual factors, it is essential to consider the circadian schedule delays that college students may adopt to fulfil social demands, as a potentially modifiable factor. The results obtained in this study could be taken into account in the design of preventive mental health programmes in the university academic setting. Among other measures, it could be interesting to adapt the shifts to the individual chronotypes of the students during the internship rotations in the hospital. Shift work may also be unavoidable for nurses; however, understanding the predictive and chronotype-related factors for nurses is crucial for nurse educators and managers in developing a reasonable shift system and strategies to help nurses and undergraduate students adjust their work to their individual chronotypes. Such measures will enhance student nurses’ mental health, work productivity during internships, and patient safety. Learning to care should begin with self-awareness and self-care. In this respect, prevention and treatment programmes for undergraduate mental health issues should carefully consider these factors, especially concerning young adult women and student nurses.