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Association between unhealthy behavior and sleep quality and duration in adolescents

Associação entre comportamento não saudável e qualidade e duração do sono em adolescentes

Abstract

Inadequate sleep has been associated with unhealthy behavior in adolescence. This study aimed to estimate the prevalence of negative sleep indicators (perceived poor-quality sleep and insufficient sleep duration) among students and to identify unhealthy behaviors associated with this outcome. This study is part of a school-based, cross-sectional survey conducted in 2011 in adolescents from Santa Catarina State, Brazil. High school students aged 15 to 19 years (n = 6,529) and enrolled in state public schools participated in the study. The students responded to a questionnaire on the number of hours slept (insufficient: < 8 h, sufficient: ≥ 8 h); perceived sleep quality (good or poor); and behavioral variables. Multinomial logistic regression was performed using reports of positive sleep indicators, and negative reports of one or two sleep indicators. Approximately 30% of adolescents reported a negative perception of sleep, indicating poor quality and insufficient duration. The use of computers/videogames (≥ 4 h/d) and excessive consumption of alcoholic beverages, salty snacks or sweets were associated with negative sleep indicators. A high number of young people displayed one or two negative sleep indicators, and it was found an association between these indicators and a number of unhealthy behaviors.

Key words:
Adolescent behavior; Brazil; Epidemiology; Sleep

Resumo

O sono inadequado tem sido associado com o comportamento não saudável na adolescência. Este estudo teve como objetivo estimar a prevalência de indicadores negativos do sono (percepção da má qualidade e duração insuficiente do sono) entre os alunos e identificar comportamentos não saudáveis associados a este resultado. Este estudo é parte de uma pesquisa de base escolar, transversal, realizada em 2011, em adolescentes do Estado de Santa Catarina, Brasil. Estudantes do ensino médio com idades entre 15 a 19 anos (n = 6.529) e matriculados em escolas públicas estaduais participaram do estudo. Os alunos responderam a um questionário sobre o número de horas dormidas (insuficiente: <8 h, suficiente: ≥ 8 h); qualidade do sono percebida (boa ou má); e variáveis comportamentais. Regressão logística multinomial foi realizada, utilizando os relatos de indicadores positivos do sono e relatos negativos de um ou dois indicadores do sono. Cerca de 30% dos adolescentes relataram uma percepção negativa do sono, indicando má qualidade e duração insuficiente. O uso de computadores / videogames (≥ 4 h/d) e consumo excessivo de bebidas alcoólicas, salgadinhos ou doces foram associados a indicadores negativos do sono. Um elevado número de jovens apresentou um ou dois indicadores negativos do sono, e verificou-se uma associação entre estes indicadores e uma série de comportamentos não saudáveis.

Palavras-chave:
Brasil; Comportamento do adolescente; Epidemiologia; Sono

INTRODUCTION

The quality and duration of sleep are important indicators of health and well-being in adolescents11 Carskadon MA, Acebo C, Jenni OG. Regulation of adolescent sleep: implications for behavior. Ann N Y Acad Sci 2004;1021:276-91.. Inadequate sleep has been associated with negative health perception, low physical aptitude, and obesity22 Dahl RE.; Lewin DS. Pathways to Adolescent Health: Sleep Regulation and Behavior. J Adolesc Health 2002;31(6 suppl.):175-84.. In addition, inadequate sleep represents signs of stress and a lifestyle that can compromise health33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3.. In adolescence, there are increases in academic demands, exposure to social and extracurricular activities and the propensity to occupy part of the time with work. Adolescents sleep insufficiently due to these social, academic and work-related pressures and to biological changes in the sleep-wake cycle11 Carskadon MA, Acebo C, Jenni OG. Regulation of adolescent sleep: implications for behavior. Ann N Y Acad Sci 2004;1021:276-91.. The consequences of insufficient and poor-quality sleep can have a negative impact on the behavioral and emotional control of adolescents, which may be associated with the adoption of unhealthy behaviors22 Dahl RE.; Lewin DS. Pathways to Adolescent Health: Sleep Regulation and Behavior. J Adolesc Health 2002;31(6 suppl.):175-84., including smoking, alcohol and illicit drug use44 Johnson E O, Breslau N. Sleep problems and substance use in adolescence. Drug Alcohol Depend 2001;64(1):1-7.,55 Vignau J, Bailly D, Duhamel A, Vervaecke P, Beuscart R, Collinet C. Epidemiologic study of sleep quality and troubles in French secondary school adolescentes. J Adolesc Health 1997;21(5):343-50., poor eating habits33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3., physical inactivity66 National Sleep Foundation. Sleep in America Poll, 2006; Available from: <http:// www.sleepfoundation.org/sites/default/files/2006_summary_of_findings.pdf> [2012 Oct 10].
http://www.sleepfoundation.org/sites/def...
,77 Tynjala J, Kannas L, Levalahti E, Valimaa R. Perceived sleep quality and its precursors in adolescents. Health Promot Int 1999;14(2):155-66. and sedentary activities88 Van den Bulck J. Television viewing, computer game playing, and Internet use and self-reported time to bed and time out of bed in secondary-school children. Sleep 2004; 27(1):101-4..

In the last years, Brazil has experienced significant changes in factors related to deteriorated sleep patterns in adolescents, especially due to the purchasing power of internet access and electronic equipment. Between 2000 and 2010, the population census recorded an increase in permanent households with televisions (from 89.0% to 96.0%) and computers (12.6% to 35.1%)99 Instituto Brasileiro de Geografia e Estatística [IBGE]. Censo Demográfico 2000 e 2010: distribuição da população brasileira e de Santa Catarina, por sexo, segundo os grupos de idade. - Rio de Janeiro: IBGE, 2012a. Available from: <http://www.censo2010.ibge.gov.br/sinopse/> [2012 May 30].
http://www.censo2010.ibge.gov.br/sinopse...
. New technological inventions (iPhones and smartphones, for example) have reduced the duration of sleep in adolescent88 Van den Bulck J. Television viewing, computer game playing, and Internet use and self-reported time to bed and time out of bed in secondary-school children. Sleep 2004; 27(1):101-4.,1010 Johnson JG, Cohen P, Kasen S, Firts MB, Brook JS. Association between television viewing and sleep problems during adolescence and early adulthood. Arch Pediatr Adolesc Med 2004;158(6):562-8.,1111 Mesquita G, Reimão R. Nightly use of computer by adolescents: its effect on quality of sleep. Arq Neuropsiquiatr 2007;65(2-B):428-32..In addition, increased nighttime leisure options encourage teenagers to stay awake until later times and can promote alcohol consumption and harm the sleep1212 Wong MM. Pubertal development, sleep problems, and alcohol use: A commentary. Alcohol Clin Exp Res 2010;34(12):2019-21..

However, despite evidence of an association between negative sleep indicators and undesirable health behaviors33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3., review studies indicate a lack of information on South American teenagers1313 Gradisar M, Gardner G, Dohnt H. Recent worldwide sleep patterns and problems during adolescence: A review and meta-analysis of age, region, and sleep. Sleep Med 2011;12(2):110-8.

14 Olds T, Blunden S, Petkov J, Forchino F. The relationships between sex, age, geography and time in bed in adolescents: A meta-analysis of data from 23 countries. Sleep Med Rev 2010;14(6):371-8.
-1515 Matricciani L, Olds T, Petkov J. In search of lost sleep: Secular trends in the sleep time of school-aged children and adolescents. Sleep Med Rev 2012;16(3):203-11.. Furthermore, a literature review revealed no studies that investigated the relationship between unhealthy behaviors and sleep quality and duration in a representative sample of schools in a Brazilian state.

The present study identified risk behaviors that are associated with insufficient and poor-quality sleep. Such information is important when trying to minimize the negative effects of economic and psychosocial factors on sleep and of biological changes in the sleep-wake cycle in adolescents. Thus, this study sought to estimate the prevalence of negative sleep indicators (perceived poor-quality and insufficient sleep duration) on school days among high school students from Santa Catarina state, Brazil, and to identify unhealthy behaviors associated with this outcome.

METHODS

Sampling design

This study is part of school-based epidemiological survey entitled "Lifestyle and behaviors of risk of young people from Santa Catarina - COMPAC project" that was performed in 2011. The population included public high school students between the ages of 15 and 19 years. The following statistical parameter was used to calculate the sample size: the unknown prevalence of the phenomenon, estimated at 50%; a confidence interval of 95%; and a maximum error of 2 percentage points, achieving a minimum sample size of 2,373 students. This study used a design effect of two (n = 4,746) and added 25% for possible losses or refusals during collection, with a final sample of 5,932 students.

The geographical regions (n = 6), comprised the sampling strata. The selection of sample units occurred in two stages: (1) schools were stratified by size (large: ≥ 500 students; middle: 200 to 499 students; and small: < 200 students), and (2) specific classes were drawn by shift and grade. A total of 90 schools were selected from the 725 available schools, and 344 classes were selected. Detailed sampling procedures have been published elsewhere1616 Silva KM, Lopes AS, Hoefelmann LP, Cabral LCA, De Bem MFL, Barros MVG, et al. Projeto COMPAC (comportamentos dos adolescentes catarinenses): aspectos metodológicos, operacionais e éticos. Rev Bras Cineantropom Desempenho Hum 2013; 15(1):1-15.. The questionnaire was tested for face and content validity, and values of reproducibility ranging from 0.51 to 0.96 were obtained (unpublished data).

The survey was approved by the Ethics Committee on Human Research of the Federal University of Santa Catarina (Process Nº: 1029/2010) and the Education Department of the state of Santa Catarina.

Descriptive variables

The duration and quality of sleep were based on self-reported data. These variables have shown good test-retest reproducibility1717 Brener ND, Kann L, McManus T, Kinchen SA, Sundberg EC, Ross JG. Reliability of the 1999 youth risk behavior survey questionnaire. J Adolesc Health 2002;31(4):336-42., as it was found in the COMPAC project (r = 0.51 to 0.96). In this study, sleep duration on school days was examined, and students were instructed to disregard daytime naps and sleep quality, which is the frequency with which they slept well. For classification, cutoff recommended by the National Sleep Foundation66 National Sleep Foundation. Sleep in America Poll, 2006; Available from: <http:// www.sleepfoundation.org/sites/default/files/2006_summary_of_findings.pdf> [2012 Oct 10].
http://www.sleepfoundation.org/sites/def...
and other studies33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3.,1818 Foti KE, Eaton DK, Lowry R, McKnight-Eily LR. Sufficient Sleep, Physical Activity, and Sedentary Behaviors. Am J Prev Med 2011;41(6):596-602.,1919 Ortega FB, Chillon P, Ruiz JR, Delgado M, Albers U, Alvarez-Granda JL, et al. Sleep patterns in Spanish adolescents: associations with TV watching and leisure-time physical activity. Eur J Appl Physiol 2010;110(3):563-73.. Detailed information can be found in box 1, which also contains the variables' respective collection methods and analysis categories.

Box 1
Description of variables, categories and collection method.

Statistical analysis

Relative frequency distribution of the outcomes under study and the outcomes' combination was used. Because no inter-sex differences were found, this stratum was disregarded in the analyses. Next, crude and adjusted multinomial logistic regression was performed using reports of positive sleep indicators (sufficient duration + good quality) as a reference against negative reports of one indicator (insufficient duration + good quality + sufficient duration + poor quality) or two (insufficient duration + poor quality). Each behavioral variable was adjusted for the other independent variables. Four control variables were used to divide the hierarchical model into four levels: (1) demographic (sex, age and residential area), (2) socioeconomic (occupation, monthly family income and schooling level of the mother and adolescent), (3) psychological (perception of health, stress level, perception of sadness and loneliness), and (4) nutritional status (body mass index). All adjustment variables were self-reported by the students on a standardized questionnaire. Variables with a critical level ≤ 0.20 remained in the model. Finally, a significance level of 5% was adopted.

RESULTS

The final sample was 6,529 students. There was sample loses in range of until 2% to sleep variables, like sleep quality perception (n = 6,447; missing: 1.9%); sleep duration perception (n = 6,496; missing: 1.1%), and their combination (n = 6,419; missing: 2.3%).

More than one-third of the students reported a negative perception of sleep quality during the week (figure 1. 1A). Regarding sleep duration, the highest proportion of teenagers reported sleeping 7 (25.8%) and 8 (26.4%) h/d. A high prevalence of students reported insufficient sleep duration (≤ 7 h), representing approximately 50% of the total (figure 1. 1B).

Figure 1
Distribution of sleep quality (A) and duration (B) perception on weekdays among adolescents. Santa Catarina, Brazil, 2011.

The proportion of students with one negative sleep indicator (poor quality or insufficient duration) did not significantly differ from those with no negative indicators (good quality + sufficient duration). Approximately 30% of adolescents reported a negative perception of sleep, indicating poor quality and insufficient duration (fig. 2).

Figure 2
Percentage of negative sleep indicators on weekdays (n = 6,419). Santa Catarina, Brazil, 2011.

In the presence of one negative sleep indicator, compared with none, engaging in < 30 min of physical activity per day was a protective factor in a crude analysis. For two negative factors, 30 to 59 min and < 30 min were associated, but these associations did not persist after adjustments. Watching TV, irrespective of the number of hours per day, was a protective factor against reporting one or two negative sleep factors. The likelihood of those individuals who used a computer/videogames ≥ 4 h/d reporting one or two negative indicators was 1.31 to 1.80 times higher, respectively, after adjustments. All food components were associated with two negative sleep indicators in a sleep analysis, but after adjustments, an inadequate intake of salty snacks and sweets (≥ 5 d/wk) remained associated with this outcome. Those individuals who consumed excessive amounts of alcohol (≥ 3 drinks/occasion) were 1.24 times more likely to report a negative indicator and 1.59 times more likely to report two negative sleep indicators than those individuals who reported not drinking, after adjustments (table 2).

Table 1
Multinomial logistic regression (crude and adjusted odds ratios) for the behavior variables associated with sleep indicator clustering. Santa Catarina, Brazil, 2011.

DISCUSSION

In our study, 34.5% of teenagers reported poor sleep quality, and 54% reported insufficient sleep duration. In Finland, 26% of boys and 23% of girls were found to sleep satisfactorily, quite poorly or very poorly77 Tynjala J, Kannas L, Levalahti E, Valimaa R. Perceived sleep quality and its precursors in adolescents. Health Promot Int 1999;14(2):155-66.. In the United States, it was found that 10% seldom or never had a good night's sleep and that 36% slept well66 National Sleep Foundation. Sleep in America Poll, 2006; Available from: <http:// www.sleepfoundation.org/sites/default/files/2006_summary_of_findings.pdf> [2012 Oct 10].
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, and approximately 70% reported insufficient sleep duration33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3.,1818 Foti KE, Eaton DK, Lowry R, McKnight-Eily LR. Sufficient Sleep, Physical Activity, and Sedentary Behaviors. Am J Prev Med 2011;41(6):596-602.. In Brazil, 39% were found to sleep ≤ 8 h in the city of São Paulo2020 Bernardo MPSL, Pereira EF, Louzada FM, D´Almeida, V. Duração do sono em adolescentes de diferentes níveis socioeconômicos. J Bras Psiquiatr 2009;58(4):231-7., compared with 54.8% in a city in southern Brazil2121 Pereira FE, Bernardo MPSL, D´Almeida V, Louzada FM. Sono, trabalho e estudo: duração do sono em estudantes trabalhadores e não trabalhadores. Cad Saúde Pública 2011;27(5):975-84..

In this study, using a computer/videogames ≥ 4 h/d and consuming ≥ 3 alcoholic drinks/occasion were associated with one or two negative sleep indicators, whereas an inverse relationship was observed with TV watching. Salty snacks and sweets intake ≥ 5 d/wk remained associated with the perception of two negative indicators.

Insufficient sleep duration on school days was associated with 10 of the 11 health-related risk behaviors in North American students, such as drinking sodas, not following physical activity recommendations and using a computer ≥ 3 h/d. The only non-association was between insufficient sleep and watching TV ≥ 3 h/d33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3.. The result obtained in another American study was similar to the present study, but only sleep duration was analyzed. Those individuals who watched TV ≥ 4 h/d were more likely to sleep a sufficient number of hours compared with non-watchers. In contrast, those individuals who used a computer ≥ 2 h/d were less likely to sleep for an adequate number of hours1818 Foti KE, Eaton DK, Lowry R, McKnight-Eily LR. Sufficient Sleep, Physical Activity, and Sedentary Behaviors. Am J Prev Med 2011;41(6):596-602..

The effect of using a computer had a greater impact on what time adolescents went to sleep compared with other activities, including watching TV2222 Knutson KL, Lauderdele DS. Sociodemographic and behavioral predictors of bed time and wake time among U.S. adolescents aged 15-17 years. J Pediatr 2009;154(3):426-30.. Using a computer/videogames has been associated with poor sleep quality and insufficient sleep in adolescents88 Van den Bulck J. Television viewing, computer game playing, and Internet use and self-reported time to bed and time out of bed in secondary-school children. Sleep 2004; 27(1):101-4.,1111 Mesquita G, Reimão R. Nightly use of computer by adolescents: its effect on quality of sleep. Arq Neuropsiquiatr 2007;65(2-B):428-32.. Nevertheless, given that only using a computer/videogames ≥ 4 h/d was associated with sleep in teenagers from Santa Catarina, more extensive investigations of these activities are needed because it has been recommended that the use of these two technologies be limited. However, there is a lack of guidelines related to the frequency and duration of use.

Associations between TV and sleep are still controversial33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3.,88 Van den Bulck J. Television viewing, computer game playing, and Internet use and self-reported time to bed and time out of bed in secondary-school children. Sleep 2004; 27(1):101-4.,1919 Ortega FB, Chillon P, Ruiz JR, Delgado M, Albers U, Alvarez-Granda JL, et al. Sleep patterns in Spanish adolescents: associations with TV watching and leisure-time physical activity. Eur J Appl Physiol 2010;110(3):563-73.,2323 Wells JC, Hallal PC, Reichert FF, Menezes AM, Araujo CL, Victora CG. Sleep patterns and television viewing in relation to obesity and blood pressure: evidence from an adolescent Brazilian birth cohort. Int J Obes (Lond) 2008;32(7):1042-9.. Foti et al.1818 Foti KE, Eaton DK, Lowry R, McKnight-Eily LR. Sufficient Sleep, Physical Activity, and Sedentary Behaviors. Am J Prev Med 2011;41(6):596-602. suggest future research to determine whether the TV is in teenagers' bedrooms and whether those teenagers reporting watching TV are actually doing so or if the set is left on during other activities. Moreover, if teenagers sleep with the TV on, they may add these hours to both the number of hours watched and sleep duration. The National Sleep Foundation (2006)66 National Sleep Foundation. Sleep in America Poll, 2006; Available from: <http:// www.sleepfoundation.org/sites/default/files/2006_summary_of_findings.pdf> [2012 Oct 10].
http://www.sleepfoundation.org/sites/def...
found that 57% of adolescents have a TV in their bedrooms and that 76% watch TV for 1 h before going to sleep. Sisson et al.2424 Sisson SB, Broyles ST, Newton Jr RL, Baker BL, Chernausek SD. TVs in the bedrooms of children: Does it impact health and behavior? Prev Med 2011;52(2):104-8. found association between having a TV in the bedroom and a lower prevalence of regular sufficient sleep.

In addition to the different ways of measuring the duration and quality of sleep, which could interfere with results, the fact that many teenagers consider TV to be both a sleep impediment and a sleep aide may be an explanation for such conflicting findings. The strategy most widely reported by teenagers for falling or staying asleep was watching TV (46.2%)2525 Noland H, Price JH, Dake J, Telljohann SK. Adolescents' Sleep Behaviors and Perceptions of Sleep. J Sch Health 2009;79(5):224-30.. Watching TV was also the third most cited reason (39.4%) for teenagers' not sleeping sufficiently. It was observed that 11% of students watched TV to fall asleep, in addition to considering watching TV to be a barrier to a good night's sleep2626 Youngstedt SD, Kline CE. Epidemiology of exercise and sleep. Sleep Biol Rhythms 2006;4(3):215-21..

Engaging in physical activity was a protective factor against sleep negative indicators, only crude analysis. Physical activity has been consistently associated with better sleep quality and longer duration33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3.,66 National Sleep Foundation. Sleep in America Poll, 2006; Available from: <http:// www.sleepfoundation.org/sites/default/files/2006_summary_of_findings.pdf> [2012 Oct 10].
http://www.sleepfoundation.org/sites/def...
,77 Tynjala J, Kannas L, Levalahti E, Valimaa R. Perceived sleep quality and its precursors in adolescents. Health Promot Int 1999;14(2):155-66.,1818 Foti KE, Eaton DK, Lowry R, McKnight-Eily LR. Sufficient Sleep, Physical Activity, and Sedentary Behaviors. Am J Prev Med 2011;41(6):596-602.. Among the benefits of regular exercise for sleep2727 Driver HS e Taylor SR. Exercise and sleep. Sleep Med Rev 2000;4(4):387-402., physical activity can help to establish regular sleep times2828 National Sleep Foundation. Adolescent sleep needs and patterns. Research report and research guide. Washington DC: National Sleep Foundation; 2000. Available from: <http://sleepfoundation.org/sites/default/files/sleep_and_teens_report1.pdf> [2012 Oct 10]
http://sleepfoundation.org/sites/default...
. However, Tynjala et al.77 Tynjala J, Kannas L, Levalahti E, Valimaa R. Perceived sleep quality and its precursors in adolescents. Health Promot Int 1999;14(2):155-66. observed an association between physical activity and perceived sleep quality in girls, and Ortega et al.1919 Ortega FB, Chillon P, Ruiz JR, Delgado M, Albers U, Alvarez-Granda JL, et al. Sleep patterns in Spanish adolescents: associations with TV watching and leisure-time physical activity. Eur J Appl Physiol 2010;110(3):563-73. found slight evidence that boys who do not obtain a sufficient amount of sleep are less likely to engage in physical activity. In a city in southern Brazil, teenagers who slept less were more active2323 Wells JC, Hallal PC, Reichert FF, Menezes AM, Araujo CL, Victora CG. Sleep patterns and television viewing in relation to obesity and blood pressure: evidence from an adolescent Brazilian birth cohort. Int J Obes (Lond) 2008;32(7):1042-9..

A number of strategies that adolescents use to help them sleep may have the opposite effect, stimulating rather than relaxing. In a study conducted by Noland et al.2525 Noland H, Price JH, Dake J, Telljohann SK. Adolescents' Sleep Behaviors and Perceptions of Sleep. J Sch Health 2009;79(5):224-30., in addition to watching TV, engaging in physical exercise before going to bed was also one of the strategies used by teenagers to fall asleep. In the United States, 32% of adolescents engaged in physical exercise 1 h before retiring to bed6. These activities may have a stimulating effect and should be avoided near bedtime. The fact that the time of day of physical activities has not been widely investigated in studies seeking to find relationships between this behavior and sleep may partially explain the conflicting results that have been found.

In our study, fruit and vegetable intake was directly associated with sleep negative indicators, but did not persist after adjustments. Excessive consumption of salty snacks and sweets remained associated with both of the aforementioned variables, even after adjustments. Individuals with poor sleep quality and insufficient duration are more likely to eat lower quantities of fruits and vegetables and more high-calorie foods derived from fat and refined carbohydrates2929 Peuhkuri K, Sihvola N, Korpela R. Diet promotes sleep duration and quality. Nutr Res 2012; 32(5):309-19..

Alcohol intake remained associated with poor sleep quality and/or insufficient sleep duration in the present study. American teenagers consuming ≥ 1 drink for one or more days in the month prior to the study were 1.64 times more likely to report insufficient sleep duration33 McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3.. Because sleep and alcohol consumption affect one another, it is unclear whether inadequate sleep increases the propensity for alcohol intake or vice versa. Wong1212 Wong MM. Pubertal development, sleep problems, and alcohol use: A commentary. Alcohol Clin Exp Res 2010;34(12):2019-21. highlights the need for longitudinal studies to determine this cause-effect relationship. Teenagers who drink alcohol regularly tend to prefer later bedtimes because this substance is usually consumed at parties and other nighttime events.

For our knowledge, this is the first study that assessed the simultaneous association between a number of unhealthy behaviors and sleep quality and duration in a representative sample of students in a Brazilian state, contributing to the epidemiological literature, given the lack of sleep research on South American teenagers1313 Gradisar M, Gardner G, Dohnt H. Recent worldwide sleep patterns and problems during adolescence: A review and meta-analysis of age, region, and sleep. Sleep Med 2011;12(2):110-8.. However, the study exhibits the following limitations: 1) it is a cross-sectional study, precluding the establishment of a cause-effect relationship; 2) the sample included only adolescents who attend school and thus is not representative of all individuals in this age range; 3) sleep duration was self-reported and subjective; and 4) insufficient or poor quality sleep may be the result of a number of sleep disorders, which were not investigated here.

CONCLUSIONS

More than one-third of high school students in Santa Catarina reported poor sleep quality, and over half reported insufficient sleep duration, which was associated with a range of unhealthy behaviors. Making adolescents aware of the importance of adopting healthy behaviors is therefore relevant to improving sleep quality and prolonging sleep duration in adolescents. It is suggested that more studies be undertaken to investigate the association between different unhealthy behaviors and sleep in teenagers and to determine the time of day and extent of these behaviors, and especially the use of electronics and physical activity, to elucidate the divergent findings reported to date.

Acknowledgments

We thank the Secretary of Education of the state of Santa Catarina and the managers, teachers and students of the selected schools. We also thank the members of the Center for Research on Physical Activity at the Federal University of Santa Catarina and are grateful for the financial support of the Foundation for Research and Innovation in the State of Santa Catarina, Brazil, and the Brazilian National Research Council (CNPq).

REFERENCES

  • 1
    Carskadon MA, Acebo C, Jenni OG. Regulation of adolescent sleep: implications for behavior. Ann N Y Acad Sci 2004;1021:276-91.
  • 2
    Dahl RE.; Lewin DS. Pathways to Adolescent Health: Sleep Regulation and Behavior. J Adolesc Health 2002;31(6 suppl.):175-84.
  • 3
    McKnight-Eily LR, Eaton DK, Lowry R, Croft JB, Presley-Cantrell L, Perry GS. Relationships between hours of sleep and health-risk behaviors in US adolescent students. Prev Med 2011;53(4-5):271-3.
  • 4
    Johnson E O, Breslau N. Sleep problems and substance use in adolescence. Drug Alcohol Depend 2001;64(1):1-7.
  • 5
    Vignau J, Bailly D, Duhamel A, Vervaecke P, Beuscart R, Collinet C. Epidemiologic study of sleep quality and troubles in French secondary school adolescentes. J Adolesc Health 1997;21(5):343-50.
  • 6
    National Sleep Foundation. Sleep in America Poll, 2006; Available from: <http:// www.sleepfoundation.org/sites/default/files/2006_summary_of_findings.pdf> [2012 Oct 10].
    » http://www.sleepfoundation.org/sites/default/files/2006_summary_of_findings.pdf
  • 7
    Tynjala J, Kannas L, Levalahti E, Valimaa R. Perceived sleep quality and its precursors in adolescents. Health Promot Int 1999;14(2):155-66.
  • 8
    Van den Bulck J. Television viewing, computer game playing, and Internet use and self-reported time to bed and time out of bed in secondary-school children. Sleep 2004; 27(1):101-4.
  • 9
    Instituto Brasileiro de Geografia e Estatística [IBGE]. Censo Demográfico 2000 e 2010: distribuição da população brasileira e de Santa Catarina, por sexo, segundo os grupos de idade. - Rio de Janeiro: IBGE, 2012a. Available from: <http://www.censo2010.ibge.gov.br/sinopse/> [2012 May 30].
    » http://www.censo2010.ibge.gov.br/sinopse/
  • 10
    Johnson JG, Cohen P, Kasen S, Firts MB, Brook JS. Association between television viewing and sleep problems during adolescence and early adulthood. Arch Pediatr Adolesc Med 2004;158(6):562-8.
  • 11
    Mesquita G, Reimão R. Nightly use of computer by adolescents: its effect on quality of sleep. Arq Neuropsiquiatr 2007;65(2-B):428-32.
  • 12
    Wong MM. Pubertal development, sleep problems, and alcohol use: A commentary. Alcohol Clin Exp Res 2010;34(12):2019-21.
  • 13
    Gradisar M, Gardner G, Dohnt H. Recent worldwide sleep patterns and problems during adolescence: A review and meta-analysis of age, region, and sleep. Sleep Med 2011;12(2):110-8.
  • 14
    Olds T, Blunden S, Petkov J, Forchino F. The relationships between sex, age, geography and time in bed in adolescents: A meta-analysis of data from 23 countries. Sleep Med Rev 2010;14(6):371-8.
  • 15
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Publication Dates

  • Publication in this collection
    May-Jun 2015

History

  • Received
    02 Dec 2014
  • Accepted
    11 Mar 2015
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