Association of chronotype pattern on the quality of sleep and anxiety among medical undergraduates – a cross-sectional study

Introduction

Chronotype represents the natural variations in the circadian rhythm, regulated by the suprachiasmatic nucleus of the hypothalamus, which controls melatonin secretion by the pineal gland [1], 2]. Light’s influence on circadian rhythms is mediated by rods, cones, and melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) [3]. However, the effects of artificial lighting are substantial and cannot be overlooked [4]. Broadly, individuals are classified as morning types (larks), evening types (owls), or intermediates, with significant variability observed [5], 6].

An evening chronotype is increasingly recognized as a correlate of mental illnesses such as anxiety, depression, and eating disorders [7], [8], [9]. Furthermore, it is linked to health conditions like obesity, sleep apnea, and cardiovascular diseases [10]. Behavioral and emotional issues, including aggression and antisocial tendencies, are also reported among evening types, particularly in younger populations [11]. Poor sleep quality and unhealthy lifestyles during adolescence are considered critical markers of future health risks [12].

College students, particularly medical undergraduates, often experience disrupted sleep patterns due to demanding academic schedules, leading to social jetlag (mismatch between biological and societal clocks) and heightened mental health concerns [13], 14]. Such disruptions negatively impact academic performance [15], with social jetlag especially affecting females [16]. High levels of anxiety, stress, depression, and substance abuse have been reported among adolescents in northern India [17], 18]. Evening chronotypes are also associated with substance abuse behaviors [19], 20].

Chronotherapeutic approaches, including interventions like blue light therapy and pharmacological agents such as agomelatine, aim to realign circadian rhythms to improve mental health outcomes [21], 22]. Encouraging evening types to adopt morning chronotypes has shown significant improvements in mental health [23], 24]. Additionally, restricting bedtime mobile phone use, which promotes eveningness, could positively impact sleep and mental health [25].

Adjusting institutional schedules to align with students’ natural chronotypes has been proposed to improve academic outcomes [26]. Since evening chronotypes are often associated with poorer mental health and academic performance [27], hence this present study is conceived to investigate the chronotype patterns among medical undergraduate students and assess their correlation with anxiety and sleep disorders.

Materials and methods

Results

In our study involving 200 Indian medical students with a mean age of 20.02 (±1.150) years, we observed that the majority of participants (76.5 %; n=152) exhibited a Neutral chronotype, as assessed by the Morningness-Eveningness Questionnaire (MEQ), with a mean score of 50.18 (±7.781) (Table 1). The gender distribution was nearly balanced, with 46 % females (n=92) and 54 % males (n=108). The prevalence of the Neutral chronotype remained consistent across various demographic and lifestyle factors, including urban vs. rural residency, body mass index (BMI), and sleep quality (Table 1).

No significant correlations were found between MEQ scores and variables such as sex, BMI, and electronic media use. However, individuals classified as evening types exhibited significantly higher anxiety levels, as measured by the State-Trait Anxiety Inventory (STAI-S and STAI-T), with mean scores of 56.09 (±4.566) and 49.09 (±6.202), respectively, compared to those with morning and Neutral chronotypes (ANOVA, F=31.798, p=0.001; F=30.294, p=0.001). These findings suggest a negative association between lower MEQ scores and higher anxiety levels (STAI-S rho=−0.497; STAI-T rho=−0.513; p=0.001 for both) (Figure 1).

Figure 1:

Comparison of mean STAI-S score and STAI-T score of morning type, evening type, and neither type individuals.

The mean global Pittsburgh Sleep Quality Index (PSQI) score was 6.00 (±2.553), with 56 % of participants reporting poor sleep quality. Evening chronotypes were found to have significantly worse sleep quality, as evidenced by higher PSQI scores (8.14±1.670) compared to morning and Neutral types (ANOVA, F=43.663, p=0.001). PSQI scores showed a negative correlation with MEQ scores (rho=−0.320; p=0.001) and a positive correlation with both STAI-S and STAI-T scores (rho=0.268, p=0.001; rho=0.195, p=0.006) (Table 2).

Discussion

Our exploration of chronotype distribution among Indian medical undergraduates provides an in-depth analysis of its diverse effects on mental health and sleep quality – two critical factors influencing academic success and overall well-being. The findings indicated that most participants fell into the ‘neutral’ chronotype category, which might reflect an ongoing period of adjustment, particularly among early-year students transitioning from structured school schedules to the more demanding routines of medical education. This transitional phase often brings challenges such as disrupted sleep patterns and heightened stress levels. Similar trends have been observed in international studies, including one conducted in Brazil [6], 13], 33]. This group, typically less aware of the role chronotype plays in well-being, constitutes a vulnerable population requiring targeted interventions [34].

Notably, as per the previous studies, students with an ‘evening’ chronotype reported significantly higher levels of anxiety and poorer sleep quality [35], which is especially concerning given the already rigorous nature of medical training. Evening chronotypes, who naturally prefer later sleep and wake times, often experience ‘social jetlag’ due to misalignment with societal schedules, leading to compromised sleep and elevated stress levels [16]. This highlights the necessity of introducing educational initiatives that promote sleep hygiene and raise awareness about the impact of chronotype on mental health [24].

From a policy standpoint, these findings hold significant implications. Academic schedules that better accommodate evening chronotypes could yield substantial benefits. For example, even modest adjustments, such as delaying class start times by an hour, have been shown to enhance academic performance and attendance [17]. Such changes could improve not only educational outcomes but also reduce stress and anxiety levels.

Additionally, evening chronotypes face a higher risk of engaging in antisocial behaviors and substance abuse [10], 11]. Therapeutic approaches like chronotherapy and blue light therapy offer promising solutions for correcting circadian rhythm misalignments, thereby fostering better mental health. These findings support the need for the National Medical Commission (NMC) to reconsider conventional scheduling practices. Aligning academic schedules more closely with students’ natural rhythms could significantly mitigate social jetlag, enhance academic performance, and improve mental well-being among evening chronotypes.

Furthermore, our study underscores the importance of educational programs that focus on sleep hygiene and chronotype awareness, empowering students to make informed decisions about their sleep and mental health. Such proactive interventions could play a pivotal role in safeguarding the health and productivity of future medical professionals.

Limitations

The nature of our study, limits the ability to draw causal inferences, underscoring the need for longitudinal studies to establish more definitive conclusions. Additionally, the study was conducted at a single academic institution, which restricts the generalizability of the findings to broader populations or different educational environments. This institutional focus may introduce selection bias, potentially skewing the results in ways that would not apply in more diverse academic settings. Furthermore, the reliance on self-reported data through questionnaires introduces the possibility of reporting bias, as participants may inaccurately recall or potentially understate or exaggerate their conditions.

Conclusions

Most medical students fall in neither/intermediate category of chronotype and evening chronotype is less common than expected. However, this may be a transitional state as they are adapting to a college lifestyle rather than high school. The evening chronotype is associated with poorer sleep quality and higher anxiety levels. Hence it is proposed to be the best time for intervention to spread awareness regarding the importance of proper sleep schedules among them to reduce anxiety and sleep-related disorders among the youth.