University and college students are particularly vulnerable to psychological distress, which can lead to the worsening or the onset of mental health conditions (1, 2). Mental health can be defined in two ways: as the absence of mental illness or as a broader concept that includes biological, psychological, and social factors influencing an individual’s well-being and ability to function (3). The Public Health Agency of Canada also describes it as the capacity to think, feel, and act in ways that foster resilience, enjoyment of life, and the ability to cope with challenges while recognizing the importance of culture, equity, social justice, personal dignity, and interconnectedness (3). Recent studies indicate that mental health challenges among university students are rising, with evidence suggesting an increase in distress and poor well-being over the past 5 years (1, 2). These issues not only pose a threat to students’ mental health but also have significant academic, social, and economic consequences (2). They can contribute to underperformance, a higher risk of insomnia and low sleep quality, reduced life satisfaction and social activity, and increased loneliness, ultimately affecting their overall well-being.

Insomnia is a sleep-related condition characterized by difficulty falling asleep, staying asleep, or experiencing non-restorative sleep despite having adequate opportunity to rest. To be diagnosed with insomnia, these sleep difficulties must occur and persist at least three times per week for at least 1 month and be associated with daytime impairment or distress (4). Among university students, insomnia is highly prevalent, with studies reporting rates ranging from 40 to 70% (5). The transition to university life introduces significant stressors, including academic workload, social changes, and irregular schedules, all of which contribute to sleep disturbances (2). Insomnia in students has been linked to impaired cognitive function, decreased academic performance, and increased risks of anxiety and depression (2, 5–7). In line with this, another study conducted in Greece during the COVID-19 pandemic reported that 65.9% of medical students had insomnia, with high levels of anxiety and depression being significantly associated with poor sleep quality (7).

Loneliness is a psychological and emotional state characterized by a sense of disconnection from others, often due to a lack of social belonging and meaningful relationships (8–10). Loneliness is a widespread and growing concern among university students, with significant implications for poor academic performance, as well as mental and physical health, including depression, anxiety, sleep problems, and increased risk of substance use (10–16). The transitions to university life, such as entering a new academic environment and facing social and academic pressures, have heightened the risk and prevalence of loneliness in this population (10, 11). The combination of academic pressure and social adjustment difficulties may lead to feelings of isolation, as students struggle to form meaningful connections in their new environment. Recent studies report that between 20 and 32% of university students experience loneliness, with some studies noting even higher rates during the COVID-19 pandemic (up to 76%) (10, 11, 14, 16–19). Key risk factors include being female or gender-diverse, younger or older age, being single, living alone, low socioeconomic status, poor health, low physical activity, and being a first-year or international student (10, 11, 13, 14, 16–20).

Furthermore, the experience of loneliness during these transitions can create a cyclical effect, where feelings of social disconnection reduce motivation to engage with peers or participate in campus activities, thereby reinforcing isolation. The lack of a stable social support system during such critical periods may exacerbate stress and hinder students’ ability to cope effectively with the demands of their new academic setting. Recognizing and addressing these vulnerabilities is essential for institutions aiming to promote student resilience and foster inclusive, supportive campus communities.

Loneliness is categorized into three primary forms: emotional, social, and existential. Both emotional (lack of close, intimate relationships) and social (lack of a broader social network) types of loneliness are prevalent among students (11, 21). Emotional loneliness arises when individuals lack close, meaningful relationships, often after losing significant people in their lives. Social loneliness occurs when individuals perceive their social network as inadequate in terms of both quantity and quality (10, 11, 22). A previous report has indicated that insomnia mediates health; it further documented that loneliness mediates the association between intergenerational relationships, as a reflection of quality of life in the aged population, and depression (23). In a previous study, loneliness correlated with lower life satisfaction among Polish, Spanish, and Slovak nursing students (22). Furthermore, loneliness was identified as a health and well-being indicator (24).

Life satisfaction is a key component of well-being, referring to an individual’s overall assessment of their life based on personal benchmarks and expectations. It encompasses both cognitive and emotional aspects, where individuals assess their circumstances in relation to their goals, desires, and past experiences (25, 26). As a broad indicator of quality of life and psychological health, life satisfaction significantly influences a person’s overall happiness and resilience. While psychological theories emphasize their importance, there is still much to uncover about the factors that shape it and its full impact on mental and emotional well-being (26, 27). A lower life satisfaction is often linked to hopelessness, which can elevate the risks of suicide. Thus, life satisfaction not only reflects overall well-being but also serves as a vital predictor of mental health outcomes (28, 29).

Beyond its connection to mental health, life satisfaction is shaped by factors such as academic experiences, social interactions, physical health, cultural influences, and individual characteristics (30, 31). Life satisfaction among university students is influenced by multiple factors, including socioeconomic status, academic performance, and quality of relationships with family and friends, with a majority reporting satisfaction in these areas (32). Cross-national studies among university students reveal that life satisfaction varies by country but consistently correlates with self-rated physical health, highlighting the universal importance of health perceptions (33). Academic stress is inversely related to life satisfaction, indicating that higher stress levels reduce students’ overall well-being (34). Additionally, cultural background and social support play crucial roles, with emotional and social health strongly predicting life satisfaction, emphasizing the need for university support systems tailored to diverse student populations (35, 36). During their studies, medical students may experience academic burnout, which can consequently reduce life satisfaction (37), whereas resilience helps counteract its effects and enhance well-being (38). Social influences, such as self-esteem and perceived discrimination, also play a role—self-esteem is particularly impactful in individualistic societies, whereas social belonging is more significant in collectivist cultures (25).

Physical health is another key determinant of well-being, with regular exercise linked to improved mood, reduced stress, and a greater sense of fulfillment (39). To understand university students’ physical health, it is essential to consider factors such as physical activity, diet, and sleep, and their impact on both physical and mental health. Although regular physical activity is crucial for maintaining physical health, university students often engage in low levels of physical activity, which is associated with poorer physical health outcomes (33, 40–44). For instance, a study in China found that 17.24% of students had low levels of physical activity, with a higher prevalence among females (44). Prolonged screen time and sedentary lifestyles also contribute to physical inactivity and mental health issues such as burnout and academic stress (41). Poor dietary habits, such as irregular breakfast consumption, low vegetable intake, and frequent consumption of sugar-sweetened beverages, are also prevalent issues that negatively impact students’ physical and mental health (45). Furthermore, irregular sleep patterns and poor sleep quality are common among university students and are associated with higher levels of stress, anxiety, and depression (41, 45, 46). Mediational analyses documented that life dissatisfaction and loneliness elevated the risks of depression, and these associations were mediated by general health (47).

A fundamental approach to understanding mental health is the biopsychosocial model (BPSM), which has been a key framework in psychiatric practice for four decades. First introduced by George Engel (48, 49). This model was developed as a response to the limitations of the traditional biomedical approach (50). At its core, the BPSM acknowledges that individuals experience illness as a whole rather than as isolated symptoms affecting specific organs. This model highlights the role of psychosocial factors in determining a person’s susceptibility to illness, symptom severity, and the overall progression of a disease (51).

This study aimed to investigate the relationship between life satisfaction and key factors such as loneliness, poor physical health, and insomnia symptoms in undergraduate students, controlling for sex as a biological key factor that has been documented to play a role in life satisfaction (52), and insomnia (53), where it prevailed in women compared to men. Gender bias was also reported to exist in general health (54). Therefore, we added biological sex as a possible confounding variable in our analysis. Furthermore, the interconnections among loneliness, poor physical health, and insomnia symptoms were investigated. Lastly, based on the biopsychosocial model of health and well-being, the study examined whether insomnia and physical health mediate the relationship between loneliness and life satisfaction, to provide a deeper understanding of the mechanisms linking these variables.

In this study, we examined the intricate relationships among loneliness, insomnia symptoms, physical health, and life satisfaction, while accounting for confounding variables such as biological sex, within a biopsychosocial framework. Our results revealed that females reported more pronounced insomnia symptoms than males. Life satisfaction declined as loneliness, insomnia, and poor physical health increased, suggesting that these factors are negatively correlated. Additionally, loneliness showed positive associations with both insomnia symptoms and poor physical health. Furthermore, our mediation analysis showed that loneliness reduced life satisfaction both directly and indirectly, by increasing insomnia symptoms and deteriorating physical health. These findings collectively underscore the mediating roles of insomnia and health status in the relationship between loneliness and life satisfaction, supporting the relevance of the biopsychosocial model in understanding student mental health.

Our study found no statistically significant differences between male and female participants in loneliness, physical health, and life satisfaction, aligning with previous research indicating that biological sex does not substantially influence overall life satisfaction. For example, an earlier study found that women reported higher levels of life satisfaction than men; however, these differences were inconsistent across age groups (52). Furthermore, Jordan et al. (66) found no significant sex differences in life satisfaction, social support, or self-esteem among undergraduate students, though Females exhibited higher gratitude levels than males (66). Regarding physical health, gender differences were reported to be a condition-based status, where it was found that men presented higher risks in some disorders. In comparison, women tend to have higher risks in other conditions (54).

Similarly, Froh et al. (67) demonstrated that the relationship between gratitude and life satisfaction did not significantly differ by gender, suggesting a shared underlying mechanism between males and females. These findings indicate that while some psychological traits may vary by biological sex and psychosocial gender, life satisfaction appears to be influenced by factors beyond sex alone. Yet, our findings suggest that insomnia symptoms vary across biological sex.

At the same time, Tang et al. (68) supported our findings regarding insomnia results. They reported that females had more sleep difficulties than males, including longer sleep latency and poorer sleep quality (68). It further supported our previous reports indicating that insomnia rates are higher in student samples composed primarily of females compared to the global prevalence (69, 70).

In line with our findings, a systematic review found that approximately 30% of university students met criteria for insomnia, and poor sleep was directly linked to academic stress and reduced performance (6). Additionally, we previously reported that a significant number of undergraduate students exhibited insomnia at higher rates (69, 70). Furthermore, another study reported a negative correlation between physical activity and insomnia, suggesting that physically active students reported fewer sleep problems (5).

Loneliness negatively correlates with life satisfaction, demonstrating its detrimental effects on well-being (71). A study on a Chinese university student sample revealed that individuals with high scores of loneliness are more prone to mood disorders, including anxiety, depression, and unhealthy coping mechanisms. Furthermore, prolonged loneliness increases the risk of long-term psychological distress, with lonely youth being three times more likely to develop depression later in life (72). In line with this, a study among health track students found that participants with higher levels of loneliness reported lower satisfaction across various aspects of life, reinforcing the idea that loneliness significantly affects mental and emotional well-being (22).

Loneliness directly reduces life satisfaction, and this is partially due to increased insomnia symptoms, which, in turn, lead to lower subjective assessments of physical health, ultimately resulting in lower life satisfaction. These results align with the biopsychosocial model of health and well-being, which highlights the interplay between psychological, physiological, and social factors in shaping individuals’ quality of life (73).

Our analysis demonstrated that insomnia symptoms and poor physical health mediate the relationship between loneliness and life satisfaction. Accumulating evidence indicates that loneliness significantly correlates with sleep disturbances, negatively affecting overall well-being (74). Hom et al. (75) found that severe insomnia symptoms were associated with greater loneliness and predicted higher loneliness levels (75). Similarly, Gu et al. (76) demonstrated that loneliness was linked to sleep disturbances, which leads to reduced mental well-being. Their findings identified insomnia as a mediator that amplifies loneliness’s negative consequences, ultimately decreasing life satisfaction. Additionally, a previous report found that loneliness was associated with poor physical health outcomes such as stroke, angina, and increased difficulty in daily activities, all of which contribute to lower life satisfaction (77).

Consistent with previous research, our study confirmed that loneliness has a direct negative impact on life satisfaction, supporting the idea that increased loneliness corresponds with lower subjective well-being. Deutrom et al. (78) demonstrated a negative association between loneliness and life satisfaction. Similarly, Kupcewicz et al. (22) found strong negative correlations between loneliness and life satisfaction among nursing students across multiple countries, highlighting the universal nature of this relationship.

This study is the first of its kind exploring this interaction among university students in Saudi Arabia. Cultural differences can exist between Saudi students and those from other countries, as suggested by research (79, 80). These differences primarily arise from Saudi Arabia’s deeply conservative, Islamic-influenced culture, which significantly impacts lifestyle. It includes a firm reliance on family and relationships, gender segregation in education and religion, and limited male–female social interaction and communication. Such cultural characteristics often present challenges for international students who adhere to more liberal norms. Saudi Arabian culture is predominantly characterized by collectivism, emphasizing group harmony, loyalty, and the importance of peer recommendations. It stands in contrast to more individualistic cultures, where personal achievement is prioritized. Islam plays a significant role in shaping daily life, social norms, and lifestyle, which can differ markedly from secular or minority-faith contexts, influencing aspects such as dress codes and daily routines. Although Arabic is the primary language, there are notable differences in non-verbal communication, such as eye contact and gestures, as well as in communication styles, necessitating adaptation, particularly for non-Arab students. While some Saudi students exhibit a positive disposition towards Western culture due to educational requirements, such as the need for English proficiency, deeply ingrained cultural values continue to influence their perceptions and interactions (79, 80). This work sheds more light on the similarities and differences between Saudi students and those from other cultural and religious backgrounds, as documented in the literature. Understanding provides better opportunities to support students in this critical phase of their lives.

Several limitations were observed in this study. Culture and religion, among other factors, need to be explored in depth to examine their relationships with insomnia, physical health, and life satisfaction. Future studies with a qualitative design are needed to investigate the impact of these factors. This study presents several noteworthy limitations that should be addressed in future research to strengthen the validity and generalizability of the findings. Primarily, the cross-sectional design restricts the ability to draw causal conclusions regarding the relationships among loneliness, insomnia, physical health, and life satisfaction. While significant associations were identified, the temporal sequence and causal pathways implied by the chain mediation model remain speculative. Longitudinal or experimental designs are essential for confirming these directional relationships and for better understanding how changes in one variable may influence others over time.

Additionally, the reliance on self-reported data introduces potential biases such as social desirability, recall inaccuracies, and response bias, which may affect the accuracy of the measured variables. Incorporating objective measures—such as medical records to verify physical health status or actigraphy to assess sleep patterns—would enhance data precision and reduce subjective bias. Furthermore, critical contextual factors such as culture and religion were not explored in depth, yet they may play a significant role in shaping experiences of insomnia, health, and life satisfaction. Qualitative studies are recommended to capture these complex influences and provide richer insights into how sociocultural dimensions interact with the variables under study, thereby offering a more comprehensive understanding of the phenomena under investigation.

In conclusion, our study underscores the importance of addressing loneliness and its associated health consequences to enhance life satisfaction among university students. The findings underscore the importance of targeted interventions that promote social connectedness, enhance sleep quality, especially in females, and promote physical well-being, ultimately contributing to a more comprehensive approach to student health and well-being.