Introduction

Sleep is essential for the preservation of the health, wellbeing and quality of human life. During sleep, the physiological functions that allow mental and physical balance take place and it has been proposed that human beings cannot live without it; therefore the concept of sleep health has been proposed and investigated in recent years¹ with studies showing that during sleep, the rejuvenation of mental processes take place²; the immunological system is activated³ and other vital functions necessary to keep an active life are completed. Sleep is controlled by the circadian rhythm which is responsible for regulating the sleep-wake cycle in periods of approximately 24 hours. At night, the secretion of melatonin -- a hormone that is involved in the sleep process - increases⁴ and it leads to more restful sleep.

The National Sleep Foundation recommends seven to nine hours⁵ of sleep for young adults 13-18 and eight or more for older people. There is, however, evidence that six hours of sleep may be enough⁶. Different studies have demonstrated a negative impact on a person’s physical and mental health based on the number of sleeping hours^7,8,9,10. Studies have shown that low quality sleep or lack of sleep affects the cardiovascular system^11,12,13and increases stress levles¹⁴. Other studies have shown a negative correlation with eating disorders^15,16. Other health issues related to poor sleep include depression, anxiety, and cognitive changes. It is essential to point out that persistent sleeping alterations represent risk factors in developing future mental illnesses and substance use disorders¹⁷.

Regular sleep consists of two types of stages: Rapid Eye Movement (REM) sleep and Non-Rapid Eye Movement (NREM) sleep. High neuronal activity is produced during REM and dreams occur. During NREM, brain activity is reduced up to 50% and is divided into three phases. The first one, or light sleep, is the shortest. The second one takes place during more than 50% of sleeping time. Finally, the third one is called Slow-Wave Sleep or Delta Sleep, the deepest and most restoring sleep^6,11.

According to the Diagnostic and Statistical Manual of Mental Disorders V (DSM-V), sleep disorders are classified into ten disorders (Table 1). Sleep disorders are also described in the International Classification of Diseases 10 (ICD-10), specifically in the point G47 and the section F51, where the non-organic sleep disorders are mentioned¹⁸.

Sleep disorders affect the academic performance of university students. Studies have shown that college students do not always exhibit the most appropriate sleep patterns. Since sleep influences human cognition, it is not surprising that students with inadequate sleep have low academic performance^19,20,21,22.

alterations in 67% of the sample²⁶. Similarly, another study involving 3011 students in Colombia, during the third phase of the COVID-19 pandemic, found that 17% of study

Therefore, the quality of sleep that students show requires attention²³.

Research during COVID-19 pandemic evidenced sleep disorders in university students. One research involving 637 university students from Oman showed the most common sleep disorders are narcolepsy (88%), Restless Legs Syndrome (41%), insomnia (36%), obstructive sleep apnea (22%)²⁴. Another study among students in Lima, Peru, demonstrated the presence of insomnia in 37.2% and hypersomnia in 2.3% of the sample¹⁴. Another research study also conducted in Peru during SARS-COV-2 found that 46.75% of sample respondents reported insomnia²⁵. A survey of 295 Colombian medical students in 2019 showed the presence of sleep respondents reported moderate insomnia and an additional 2% reported severe insomnia. Thirty-six percent of study respondents reported depression and 32% reported anxiety²⁷.

In research study conducted early in the pandemic among 644 Mexican university students, it was found that 36.3% of the sample presented insomnia²⁸. A study in El Salvador, found that approximately 50% of the sample respondents reported experiencing insomnia related to the pandemic which included difficulty falling sleep, night awakenings, final awakening earlier than desired, and somnolence during the day²⁹.

Materials and Methodology

The purpose of this study was to evaluate sleep disorders among a sample of college students in three different countries 12 months after the onset of COVID-19. The study population consisted of 693 university students in El Salvador (52.1%,) United States (20.2%), and Mexico (27.7%). The vast majority (75%) was female and 1% preferred not having their gender identified. The reported age range was between 17 and 60 years old, which a mean of 23.76 (SD = 5.99).

Data were collected using the Student Health Behavior Inventory which was based on scales designed to evaluate sleep disorders^30,31. Researchers developed questions that included aspects necessary for the research project; specifically, responses indicated if these symptoms were derived from the COVID-19 pandemic. The preliminary version of this instrument was composed of nine items. However, two questions were removed after confirmatory factor analysis since they did not fit statistically to the evaluated variable. The final instruments consisted of seven questions, which evaluate sleep patterns during the previous seven days (e.g. During the pandemic, How many days a week have you had trouble falling asleep?). The scale response was the Likert 5-points scale, where 1 = Not any day at all, 2 = One or two days, 3 = Three days, 4 = Four or five days, and 5 = Six or seven days.

Institutional review boards at the participating institutions approved the study. Data were collected using the Qualtrics platform over an eight-week period (February and March 2021). All students provided informed consent by acknowledging the purpose of the study, electronically signing and informed consent form, and completing the instrument. Data analysis was performed in SPSS (v26) for reliability analysis and descriptive statistics. A confirmatory factor analysis took place using AMOS; taking into consideration the goodness-of-fit indicators recommended by Valdes³²: Chi-square with associated probability (p <, 001), Root Mean Square Deviation (RMSD < .05), Goodness-of-Fit Indicators (GFI > .90), Comparative Fit Index (CFI < .95) and Root Mean Square Error of Approximation (RMSEA <. 07).

Reliability was obtained through Cronbachs’ alpha; subsequently, an index was calculated using the means of the seven reactive from the final scale. Later, an analysis of Variance (ANOVA) was performed to compare the means according to the country, and a Student t-test was performed to analyze statistical differences based on participants’ gender. It is essential to highlight that only eight people decided not to specify their gender, so they were not considered in this analysis, but included in all others.

Results

The Confirmatory Factor Analysis (CFA) obtained acceptable goodness-of-fit indicators: X2 = 28.29 (df = 10; = p =. 002), RMSR = .029, GFI = .99, CFI = .99. RMSEA = .051 (90%; IC = .030 - .074). Factor weight oscillated between .30 and .82 (Figure 1). Reliability analysis revealed a Cronbach´s Alpha of .85 for the final version of seven items.

Figure 1 Confirmatory Factor Analysis model. Source: Authors 

An Analysis of Variance (ANOVA) was performed to determine differences between the three countries. Differences were found in the sleep disorders reported by students in El Salvador, United States, and Mexico [F = 23.79 (df = 2, 690), p = .000] as shown in Table 2. Further comparisons pointed out statistical differences among groups with probability values oscillating between .000 and .020.

Finally, a means comparison to explore sleep disorders by gender was conducted using a student t-test for independent samples. Findings suggest differences between men and women in all three countries (see Table 3). Women reported more frequency of sleep disorders during the pandemic [Mean = 2.39 (SD = .88), t = 3.45 (df = 682), p = .001].

Discussion

The COVID-19 pandemic brought along multiple psychological affections worldwide³³. Among university students, these effects included lifestyle adjustments including attending classes through technology, performing activities, studying extra time, and in some cases, working and studying simultaneously. Given the uncertainty related to COVID -19, university students are more likely to develop sleep disorders, specifically, in the American continent. The Confirmatory Factor Analysis indicates that the scale has an acceptable validity to evaluate sleep disorders due to the COVID-19 pandemic in university students. Also, it has an acceptable reliability index.

It is interesting that while sleep disorders were found in all three countries differences were present in a north-south direction with students in the US reporting higher levels of sleep disorders while students in El Salvador reported the lowest levels. Social isolation affected all countries, but the response seems to be of increased anxiety represented as sleeping disorders among North American students. These differences may be related to social support networks available to students in Mexico and in El Salvador which are not available to students in the United States. It has been suggested that the ravages of COVID-19 are presented differently in the countries, especially due to the different forms of action each society takes around this situation³⁴.

Gender differences were not totally unexpected. Latin American females reported higher levels of sleep disorders. Results suggest that female’s mental health tends to be more affected, probably due to the responsibility of house chores being assigned to this gender³⁵, joining to the fact that the more time people are at home, these types of activities increase. It seems fair to conclude that female’s responsibilities increased as a result of spending more time at home with other relatives while leaving less time to focus on their studies or other activities.

There are some limitations inherent in this study. The first is the self-reported nature of the data. Social desirability could be present in some responses from participants; however, in the obtained results, data support reliability and validity of the instrument. Another constraint is the cross-sectional nature of the study. There is no baseline data to compare the sleep disorders in students before and after one year of social isolation; however, despite the limitations, it is considered that the information provided by this research can be useful in providing resources to students who may be experiencing sleep disorders.

Conclusión

Research suggests social isolation related to COVID 19 has resulted in sleeping disorders among college students. In our study, statistical differences were found by gender and country of origin; however, this is a snapshot of students after one year of virtual education derived from COVID-19 pandemic, with no baseline data for comparison. Future research could replicate this study, taking into account more countries from the American continent to make wider contrasts. Lastly, it is recommended that educational institutions perform research periodically, evaluating sleep disorders and other psychological alterations that are developing in this pandemic period.