Insomnia is a common sleep disorder characterized by trouble falling asleep, staying asleep, or experiencing restful sleep, even when conditions are appropriate for sleep. ^{1, 2} Multiple factors play a role in the development of insomnia, with stress being a primary contributor due to its two-way relationship with the disorder. ³ Other risk factors include demographic characteristics (such as being female, living alone, and old), genetic influences (like a family history of insomnia), respiratory issues (including asthma and sleep apnea), mental health conditions (such as anxiety and depression), and certain lifestyle habits (obesity, excessive caffeine intake, alcohol use, and smoking). ⁴

Due to the intense demands of clinical training and the extensive academic workload, medical students are especially vulnerable to high levels of stress, which can adversely affect their sleep quality and contribute to the onset of insomnia and other sleep disorders. ^{5– 7} Insomnia may negatively influence students' academic performance and overall health. Studies show that medical students experiencing insomnia often have lower Grade Point Averages than those without sleep difficulties. ^{8, 9} Some students tend to use non-prescribed hypnotics or tranquilizers as a means of managing their sleep problems. ¹⁰

Sleep disturbances are reported more frequently among medical students compared to those in other academic fields. ³ Research has identified insomnia prevalence rates of 27.8% among medical students in China and 39.4% in India. ^{11, 12} Likewise, insomnia is widely recognized as a common sleep disorder within the Arab region. ^{13– 15}

In Iraq, medical students have faced unique and ongoing challenges, such as political instability, economic difficulties, and security issues, which contributed to the high prevalence of insomnia within this group. ^{16, 17}

This survey aims to assess the prevalence of insomnia among a sample of medical students, and to highlight its relation to stress as a potential predictor.

The total number of participants was 452 medical students, with a mean age of 21.43±1.912 years (range = 17–27 years). Female students (259) formed 57.3%, while males (193) formed 42.7%% of the sample. Students in the preclinical stage (first three years of medical study) formed 52.7%, while those in the clinical stages (4 ^th, 5 ^th, and 6 ^th years) formed 47.3% of the sample, as showed in Table 1, which also demonstrates that 72.8% of the participants reported having insomnia, while 31.6% had high perceived stress level.

Table 2 shows a statistically significant relation between level of stress and insomnia (p < 0.001). Level of stress was significantly associated with gender (p < 0.001). The prevalence of insomnia among females was 42.5%, which is higher than that among males (30.3%), as demonstrated in Figure 1. However, there was no statistically significant association between insomnia and gender (p = 0.457). The results indicated that the prevalence of insomnia among students in the pre-clinical stages was 76.5%, while it was 69% among students in the clinical stages. Statistical analysis showed no significant association between insomnia and academic year (p = 0.363), or between stress and academic year (p = 0.448) ( Table 3).

Logistic regression model revealed that students with high perceived stress had OR of 3.188 for insomnia compared to those with low level of stress (C.I. 2.1-4.8, P < 0.001). The association of insomnia with gender or age was insignificant ( Table 4).

Medical students frequently face high levels of stress due to long study hours, frequent exams, and the intense demands of clinical training. This persistent stress can lead to insomnia, making it difficult to fall asleep or maintain restful sleep. ^{6, 22} The present study tried to explore the relationship between stress and insomnia, driven by the observation that many medical students engage in poor sleep habits, such as inconsistent sleep schedules and insufficient sleep duration. These sleep difficulties—along with symptoms like fatigue, reduced cognitive performance, and mood disturbances—can significantly affect their academic success, overall well-being, and quality of life.

The findings of this study indicate a significantly high prevalence of insomnia among medical students, consistent with findings from previous studies across the region. Reported rates of poor sleep quality include 76% in Saudi Arabia, 55.7% in Egypt, 70.2% in Jordan, and 37.1% in Lebanon. ^{23– 25}

In the Iraqi context, several factors likely contribute to elevated stress and insomnia rates, including ongoing security instability, exposure to violence, economic challenges, political uncertainty, overcrowding, difficult living conditions, social tensions, and limited access to mental health support. ²⁶

This study also revealed a high overall level of stress among medical students, consistent with earlier findings in Iraq, where 30.2% reported experiencing high perceived stress. ²⁷ Comparable levels were observed in other studies—using various stress assessment tools—in both developed and developing nations, including 30.9% in Egypt, 28.9% in Saudi Arabia, and 49.9% in Singapore. ²⁸

Insomnia was found to be more common among females than males. Multiple studies have indicated that female medical students are more likely to experience higher levels of insomnia and stress compared to their male counterparts. ^{29, 30}

Students with elevated stress levels showed a greater occurrence of insomnia than those with lower stress levels. Although stress was significantly associated with gender in favor of females, the association between gender and insomnia was not significant, probably because females are more resilient than males due to biological and cultural factors. ³¹ Logistic regression analysis reinforced this result, revealing that stress significantly increases the risk of insomnia, thereby confirming the hypothesis that stress is a key contributing factor to the development of insomnia.

Additionally, the study observed a higher prevalence of insomnia among students in the preclinical phase compared to those undergoing clinical training, although no significant link was found between insomnia and academic year. This pattern might be attributed to that clinical-stage students are adapting better to academic demands and managing their sleep schedules more effectively than preclinical students. Interestingly, these findings differ from a study conducted in Saudi Arabia, which reported a higher rate of insomnia among medical students in clinical stages compared to those in preclinical stages. ³²

The prevalence of insomnia among medical students is high, with a significant association with stress, suggesting that stress is an important factor contributing to insomnia among medical students. It is important to raise the awareness of medical students about how stress exacerbates sleep problems and reflects on general health and wellbeing through short education programs that helps build their resilience.

This is an observational study that did not involve any human intervention. The study was approved by the Ethical and Scientific Committee for research in College of Medicine/University of Fallujah, under approval SC NO. 2022/3 UOF.