ASSOCIATION OF SOCIODEMOGRAFIC FACTORS AND SLEEP QuALITY IN BRAZILIAN uNIVERSITY STuDENTS

The aim of this study was to analyze relationship between sociodemographic factors and poor sleep quality in Brazilian university students. Cross-sectional study, surveyed 701 students in Fortaleza, Ceará, Brazil. We applied a questionnairre with sociodemographic questions and Pittsburgh Sleep Quality Index. We did not identify associations and/or statistically significant linear trends between sleep quality and sociodemographic analyzed factors. However, the analysis found that the relative risk in college aged ≥ 31 years, in those who lived alone and with relatives (other than parents) there is greater vulnerability to poor sleep quality. DESCRIPTORS: Sleep. Sleep disorders. Students. RELAÇÕES ENTRE FATORES SOCIODEMOGRÁFICOS E QuALIDADE DO SONO EM uNIVERSITÁRIOS BRASILEIROS RESuMO: O objetivo deste artigo foi analisar a relação entre fatores sociodemográficos e a má qualidade do sono de universitários brasileiros. Estudo transversal que entrevistou 701 alunos de Fortaleza, Brasil, em 2011. Foi aplicado um formulário com questões sociodemográficas e o Índice de Qualidade do Sono de Pittsburgh. Não identificamos associações e/ou tendências lineares estatisticamente significantes entre a qualidade do sono e os fatores sociodemográficos analisados. Todavia, na análise do risco relativo constatamos que nos universitários com idade ≥ 31 anos, naqueles que moravam sozinhos e com parentes (diferentes dos pais) há maior vulnerabilidade em relação à má qualidade do sono. DESCRITORES: Sono. Transtornos do sono. Estudantes. ASOCIACIÓN ENTRE FACTORES SOCIODEMOGRÁFICOS Y CALIDAD DEL SuEÑO EN ESTuDIANTES uNIVERSITARIOS DE BRASIL RESuMEN: El propósito de este trabajo fue identificar la asociación entre los factores sociodemográficos y de mala calidad del sueño en estudiantes universitarios brasileños. Estudio transversal entrevistó a 701 estudiantes de Fortaleza, Ceará, Brasil en 2011. Se aplicó un formulario con preguntas demográficas y el Índice de Calidad del Sueño de Pittsburgh. No identificamos asociaciones y/o tendencias lineales estadísticamente significativas entre la calidad del sueño y lós factores sociodemográficos analizados. No identificamos asociaciones y/o tendencias lineales estadísticamente significativas entre la calidad del sueño y lós factores sociodemográficos analizados. Sin embargo, el análisis encontro que el riesgo relativo de lós estudiantes universitarios con edad ≥ 31 años, lós que vivian solos y familiares que no tienen mayor vulnerabilidad a mala calidad del sueño. DESCRIPTORES: Sueño. Transtornos del sueño. Estudiantes. 176


ABSTRACT:
The aim of this study was to analyze relationship between sociodemographic factors and poor sleep quality in Brazilian university students.Cross-sectional study, surveyed 701 students in Fortaleza, Ceará, Brazil.We applied a questionnairre with sociodemographic questions and Pittsburgh Sleep Quality Index.We did not identify associations and/or statistically significant linear trends between sleep quality and sociodemographic analyzed factors.However, the analysis found that the relative risk in college aged ≥ 31 years, in those who lived alone and with relatives (other than parents) there is greater vulnerability to poor sleep quality.

INTRODuCTION
Biological clocks keep close relation to several human physiological variables such as blood pressure, immune system, blood coagulation, and gastric, endocrine and renal functions, as well as sleep.However, individual characteristics such as role in the family, response to stress and lifestyle can influence sleep hygiene.Some authors have shown that some sociodemographic variables may influence even chronotypes of the subjects.Besides morningness and eveningness, sleep hours can suffer local influences.] The sleeping habits result from a complex interaction of sociodemographic, behavioral, psychological and health factors.] Previous studies correlated sleep durations to sociodemographic variables among adults, middle-aged and old people however, those investigations have not evaluated the quality of sleep.][5] Nowadays, poor sleep quality among university students is a public health problem all around the world.This is consequence of In the last decades, the growing access to new technologies has changed university students' cultural habits and life style worldwide.[10] As far as we are concerned, there are no researches associating the quality of sleep among university students with sociodemographic variables.In addition, in Brazil, there are few studies published on the sleep of university students.2][13] Thereby, this article aims to identify the associations between sociodemographic factors and poor sleep quality among Brazilian university students.

METHOD Design and population
Cross-sectional study during February to June 2011 at the Federal University of Ceará, Fortaleza, Ceará, Brazil.The target population was undergraduate students, of both sexes, duly enrolled in this university campuses in the city of Fortaleza-CE.In this period, the estimated university population was 17,228 students, divided into six major areas of knowledge: humanities, sciences, agricultural sciences, health sciences, technological sciences, and sciences.
We calculated a simple random sample without replacement, using a formula to infinite populations.We adopted a rate of 50% (P = Q = 50% and 50%) considering this value provides a maximum sample size, when set the significance level (α = 0.05) and the relative sampling error of 8% (error absolute = 4%).The sample resulted in 600 subjects.We estimated a rate of 10% for replacement questionnaires with wrong answers and/or incomplete and refusals.The final size of the sample totaled 701 students.

Measurements
The students answered a questionnaire containing five sections.The section used in this study refers to sociodemographics and sleep quality data.

Sleep quality was assessed based on a validated version, translated and adapted to Brazilian pattern of Pittsburgh Sleep Quality Index (PSQI).
It consists of ten questions, with a maximum score of 21 points, which include seven components related to the quality of sleep within past month.The students with score above five points were classified as poor sleepers. 14The demographic characteristics were sex, age, color, monthly income, economic class, the person who the student lives with, marital status and employment.

Data collection
Occurred from February to June the year 2011.Three nurses were responsible for data collection and underwent a six-hour training to become familiar with the instruments and ensure the reliability of data collected.Some college coordinators refused research authorization.Thereby, two undergraduate courses were selected by convenience from each knowledge area.Respondents studied different current year.They were invited to participate in the survey in classroom, after the explanation of the methods and goals of the study.Students answered two questionnaires, sociodemographics and other referent to sleep quality.

Data analysis
Inicially, data were entered in an Excel spreadsheet, and after typing were exported to statistical software STATA version 8.0.Data processing consisted in validating the internal consistency, calculation of descriptive measures (mean, standard deviation and median) and absolute and relative frequencies.
The differences between the sociodemographic and PSQI proportions were tested using the chi-square and Fisher exact's test.Proportional trends between the ordinal variables and PSQI were tested using the chi-square test for linear trend.Kruskal-Wallis test was used to compare differences in PSQI scores for knowledge area.
Prevalence of the PSQI was used as a measure of frequency and prevalence ratio (PR) as measure of association (95%, confidence interval [IC]) depending on the estimated relative risk (RR) of Poisson robust regression.Poisson robust regression was used due to high prevalence of poor sleep quality found in population (95.3%). 15In all analyzes, we adopted the statistical significance level of 5% (p ≤ 0.05 ).

Ethical aspects
This research was approved by the Ethics Committee on Human Research of Health Sciences Center, Federal University of Ceará, protocol n. 208/2010.

RESuLTS
The studied population comprises 701 university students from six academic areas, distributed in 24 graduation courses.Most participants were females (62.7%), and the sample's average age was 21.5 years old (DP± 4.5 years).The age variable has shown an asymmetric distribution to the right (Kolmogorov Sminorv with p<0.001).
Almost all participants were single (93%), lived with their parents (71.2%), and just studing for living (65.2%).Most of them were from socioeconomic classes C (39.6%) and B (39.7%).These students had a familiar monthly income of U$ 1.705 dollars (DP±200).It must be pointed out that 15% of the participants did not inform their monthly income value, and this variable presented an asymmetric distribution to the right (Kolmogorov Sminorv with p < 0.001).
In the analyzed sample, there was a 95.3% prevalence of poor sleep quality, what gives to the studied event a common outcome.It could be verified that the obtained association measures were similar regarding to sociodemographic characteristics and outcomes in both groups.The proportion for poor and good sleepers was higher among females students (p=0.390).In both groups, there was a predominance of single undergraduates (p=0.820),who lived with their parents, it had pale skin (p=0.576) and that only studied for a living (p=0.436).Most poor sleepers were 16 to 20 (50.3%) or 21 to 25 years old (40.2%) (p=0.87),they also be longed to socioeconomic class B (40%) (p=0.29).However, in none of these associations there were statistically significant differences between good and poor sleepers (Table 1).
No statistically significant differences ocurred between the mean of PSQI score by knowledge area (p=0.706).The mean and median PSQI score values in almost all areas of knowledge was approximately 9 (DP ≈ 1.9 to 2.5), except for the human health areas and when media was 10 points.Human and health sciences areas showed greater variations.
It was found percentages higher than 90% of poor sleep quality among both freshmen and veterans.From these, most poor sleeper participants (56.8%) were freshmen (ones studying the college first or second year).All the evaluated undergraduates from the last terms (fourth to sixth years) were classified as poor sleepers.Furthermore, there was not a significant statistically correlation between academic term and sleep quality (p=0.137)(Table 2).The results showed a positive and statistically significant association between age and poor sleep quality among the researched subjects.Among undergraduates aged ≥ 31 years, the chan-ces of poor sleep quality occurrence was 1.05 times higher (IC 95% 1.02-1.07)than among students aged 16 to 20 years old (p<0.001)(Table 3).It was evidenced a positive and statistically significant association between living alone or with relatives and poor sleep quality.In those cases, the chance of an undergraduate who lives alone or with parents to present poor sleep quality was 1.05 (p<0.001) and 1.03 (p=0.020)higher, respectively, than ones of those students who live with their spouse, friends and other relatives.The undergraduates from socioeconomic class C and those with monthly income between U$ 290 and 870 dollars also showed greater chances of poor sleep quality occurrence (Table 3).

DISCuSSION
In this research, it was not verified statistically significant association between gender and sleep quality among university students.][23][24][25][26] Women between 18 and 24 years go to bed and wake up earlier than men, but both genders showed equivalent amounts of total sleeping time, number of awakenings during the night and day naps.Other non-biological factors, as role in the family, response to stress and life style may also be involved with gender differences.For example, it was reported that childcare and partner's sexual disorders are the two main causes of young women nocturnal awakenings. 27his research identified greater vulnerability to poor sleep quality between economic class C college students and those with monthly income only 290-870 dollars.Epidemiological studies have found robust evidences that economic situation is a predictor for nocturnal sleep quality.][29][30][31][32] Currently, there is a massive diffusion of technologies such as social networks, mobile devices with internet access and many applications that keeping their attention at times for the rest, and consequently hinder the latency and sleep efficiency.Technological resources are even more accessible to young people of higher socioeconomic status.The labor demand for these young people, especially those with less favorable socioeconomic conditions, lead great effort in their academic activities in order to maintain or improve their pattern current life.Inevitably, this might also be involved in the genesis of sleep problems.
This divergence occurred due to these studies have been carried out more than five years ago.At that time, the massive spread of technology, as social networks, mobile phones with internet connection and applications, had not happened yet.These technologies may catch young people's attention in moments they should be resting, what, consequently, makes latency and sleep efficiency more difficult.
Despite of the increase on technological resources offer they are still more available for the young people on a good socioeconomic situation.Furthermore, current working competition demands great effort on academic activities, even for those in a good socioeconomic situation, in order to keep or improve one's pattern of living.This might also be inevitably related to the sleeping problems origin.
This research has not found relationship between academic area of knowledge and quality of sleep.][35] In this cases, the preponderant variable is not the academic area the undergraduate studies, but his/her life style, which increases his/her vulnerability to sleep disorders.However, even a fulltime student, who faces many academic exigencies, is able to study efficiently as well as have some pleasure and maintains his/her social life in such a way that his/her sleep quality is not impaired.
This research identified that students who live alone or with relatives (other than parents) have more chances to be poor sleepers compared to those who live with a partner(a), friends and their parents.
Regarding those who live alone, this is not surprising, because the sudden freedom experienced by these young people when they go to College can cause a situation of sleep deprivation and serious health problems.They go through stressing situations as home maintenance, noise environments and bad accommodations, especially those who adopt free academic quarters. 26,36 ving alone increases the sleep health vulnerability because one does not realize that suffers from problems as snoring, Restless Legs Syndrome or even Sleep Apnea.All these situations depend on external observation to be detected.
By the other hand, living with parents acts as a relaxing factor and good sleep preditor for these students.Regarding students who live with friends, there is also an improvement of sleep because they alternate schedules for study and leisure with friends. 24enerally speaking, universities can reduce these problems with some arrangements, such as: insalubrities reduction at the academic housings and sleep health services offer, which focus on prevention and treatment.This fact must be taken into account, mainly, at the great Universities, which routinely receive students from different places and even different countries.
This research has also investigated the statistically significant correlation between aging and poor sleeping quality.8][39] Moreover, the distance between ones biological and chronological ages makes this comparison difficult. 40][42][43] Based on this research results and the evidences pointed out by literature, changes detected in middle-aged and old people have not necessarily started at these ages.They are part of a sleep evolutionary process which may have started before the senescence.Therefore, it is fundamental to give attention to undergraduate's sleep because these young individuals may already present discrete sleep disorders that will get chronic over time and make several chronic health problems possible.

CONCLuSION
University students with good socioeconomic profile, who live alone or with their parents, and who are older than 31 years have more chances to present poor sleep quality.Undergraduates from Agricultural Sciences and Technology have shorter sleep duration than students from Sciences, Humanities, Health Sciences and Exact Sciences.Health professionals who work with school health at Universities should pay attention to sociodemographic characteristics which increase the undergraduates' vulnerability related to poor sleep quality.Based on research results, nurses may also develop health education considering this issue in student's context.

Table 1 -Sociodemographic characteristics of university students association to sleep quality (n=701). Fortaleza, Brazil, 2011.
Association of sociodemografic factors and sleep quality in...
Association of sociodemografic factors and sleep quality in... Prevalence Ratio: estimated based on robust Poisson regression adjusted by age and gender.