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Adolescent sleep disparities: sex and racial/ethnic differences

Published:January 14, 2015DOI:https://doi.org/10.1016/j.sleh.2014.12.003

      Abstract

      Objectives

      During adolescence, significant changes occur in sleep (eg, decreased sleep duration and increased sleep problems). To date, few studies have examined whether self-reported sleep duration differences exist between races/ethnicities in early adolescence (ages 11-14 years).

      Methods

      This study compared sexes and race/ethnicity groups on self-reported sleep duration in a large (n = 1543; 48.9% boys) racially/ethnically diverse (62.7% White, 23.7% Hispanic/Latino, 10.4% African American, and 3.2% Asian) sample of young adolescents (mean age, 12.31) drawn from local middle schools.

      Results

      A 2-way analysis of variance revealed that there was a trend for a significant sex effect (P = .067, partial η2 = .002), with boys reporting more sleep than girls and significant race/ethnicity effects (P < .001, partial η2 = .012), with Hispanic and African American students reporting shorter sleep duration than White and Asian students. The interaction between sex × race/ethnicity was significant (P = .014, partial η2 = .002), with post hoc tests revealing that Hispanic males demonstrated significantly shorter sleep duration than White and Asian males and African American females demonstrating significantly shorter sleep duration than White females.

      Conclusions

      Given the literature showing short sleep duration is related to various negative health outcomes and all-cause mortality, more research is needed to determine the factors involved in these disparities.
      Adolescent sleep disparities: sex and racial/ethnic differences.
      Racial/ethnic health disparities rank among the nation's foremost health challenges.
      • U.S. Department of Health and Human Services (HHS)
      Office of Disease Prevention and Health Promotion, Healthy People 2020: Rockville, MD.
      • National Partnership for Action to End Health Disparities
      National Stakeholder Strategy for Achieving Health Equity.
      • Institute of Medicine
      Unequal treatment: confronting racial and ethnic disparities in health care.
      In addition to environmental factors, social experiences, and health care quality and access issues, behavioral factors are also robust predictors of these outcomes.
      • Anderson N.B.
      Behavioral and sociological perspectives on ethnicity and health: introduction to the special issue: American Psychological Association.
      • Pampel F.C.
      • Krueger P.M.
      • Denney J.T.
      Socioeconomic disparities in health behaviors.
      Sleep is increasingly conceptualized as a health-relevant behavior,
      • Cappuccio F.P.
      • D'Elia L.
      • Strazzullo P.
      • Miller M.A.
      Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies.
      with shorter sleep being related to a variety of negative health outcomes such as type 2 diabetes,
      • Cappuccio F.P.
      • D'Elia L.
      • Strazzullo P.
      • Miller M.A.
      Quantity and quality of sleep and incidence of type 2 diabetes a systematic review and meta-analysis.
      hypertension,
      • Wang Q.
      • Xi B.
      • Liu M.
      • Zhang Y.
      • Fu M.
      Short sleep duration is associated with hypertension risk among adults: a systematic review and meta-analysis.
      cardiovascular disease and events,
      • Cappuccio F.P.
      • Cooper D.
      • D'Elia L.
      • Strazzullo P.
      • Miller M.A.
      Sleep duration predicts cardiovascular outcomes: a systematic review and meta-analysis of prospective studies.
      obesity,
      • Cappuccio F.P.
      • Taggart F.M.
      • Kandala N.-B.
      • Currie A.
      Meta-analysis of short sleep duration and obesity in children and adults.
      • Chen X.
      • Beydoun M.A.
      • Wang Y.
      Is sleep duration associated with childhood obesity? A systematic review and meta-analysis.
      hypercholesterolemia,
      • Gangwisch J.E.
      • Malaspina D.
      • Babiss L.A.
      • Opler M.G.
      • Posner K.
      • Shen S.
      • et al.
      Short sleep duration as a risk factor for hypercholesterolemia: analyses of the National Longitudinal Study of Adolescent Health.
      • Gangwisch J.E.
      • Heymsfield S.B.
      • Boden-Albala B.
      • Buijs R.M.
      • Kreier F.
      • Pickering T.G.
      • et al.
      Sleep duration as a risk factor for diabetes incidence in a large U.S. sample.
      and all-cause mortality.
      • Cappuccio F.P.
      • D'Elia L.
      • Strazzullo P.
      • Miller M.A.
      Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies.
      • Gallicchio L.
      • Kalesan B.
      Sleep duration and mortality: a systematic review and meta-analysis.
      Short sleep duration has also been associated with psychological outcomes such as depression, anxiety,
      • Ivanenko A.
      • Crabtree V.M.
      • Gozal D.
      Sleep and depression in children and adolescents.
      and substance abuse
      • Alfano C.A.
      • Zakem A.H.
      • Costa N.M.
      • Taylor L.K.
      • Weems C.F.
      Sleep problems and their relation to cognitive factors, anxiety, and depressive symptoms in children and adolescents.
      as well as deficits in cognitive functioning,
      • Gromov I.
      • Gromov D.
      Sleep and substance use and abuse in adolescents.
      attention,
      • Perez-Lloret S.
      • Videla A.J.
      • Richaudeau A.
      • Vigo D.
      • Rossi M.
      • Cardinali D.P.
      • et al.
      A multi-step pathway connecting short sleep duration to daytime somnolence, reduced attention, and poor academic performance: an exploratory cross-sectional study in teenagers.
      • Beebe D.W.
      • Rose D.
      • Amin R.
      Attention, learning, and arousal of experimentally sleep-restricted adolescents in a simulated classroom.
      and academic performance.
      • Perkinson-Gloor N.
      • Lemola S.
      • Grob A.
      Sleep duration, positive attitude toward life, and academic achievement: the role of daytime tiredness, behavioral persistence, and school start times.
      Previous literature documents sex and racial/ethnic differences in sleep duration in adults,
      • Hale L.
      • Do D.P.
      Racial differences in self-reports of sleep duration in a population-based study.
      • Unruh M.L.
      • Redline S.
      • An M.W.
      • Buysse D.J.
      • Nieto F.J.
      • Yeh J.L.
      • et al.
      Subjective and objective sleep quality and aging in the sleep heart health study.
      • Beatty D.L.
      • Hall M.H.
      • Kamarck T.A.
      • Buysse D.J.
      • Owens J.F.
      • Reis S.E.
      • et al.
      Unfair treatment is associated with poor sleep in African American and Caucasian adults: Pittsburgh SleepSCORE project.
      • Durrence H.H.
      • Lichstein K.L.
      The sleep of African Americans: a comparative review.
      • St-Onge M.P.
      • Perumean-Chaney S.
      • Desmond R.
      • Lewis C.E.
      • Yan L.L.
      • Person S.D.
      • et al.
      Gender differences in the association between sleep duration and body composition: the Cardia Study.
      with women sleeping longer than men
      • Hale L.
      • Do D.P.
      Racial differences in self-reports of sleep duration in a population-based study.
      • Unruh M.L.
      • Redline S.
      • An M.W.
      • Buysse D.J.
      • Nieto F.J.
      • Yeh J.L.
      • et al.
      Subjective and objective sleep quality and aging in the sleep heart health study.
      and African Americans and Hispanics sleeping less than Whites.
      • Beatty D.L.
      • Hall M.H.
      • Kamarck T.A.
      • Buysse D.J.
      • Owens J.F.
      • Reis S.E.
      • et al.
      Unfair treatment is associated with poor sleep in African American and Caucasian adults: Pittsburgh SleepSCORE project.
      • Durrence H.H.
      • Lichstein K.L.
      The sleep of African Americans: a comparative review.
      • St-Onge M.P.
      • Perumean-Chaney S.
      • Desmond R.
      • Lewis C.E.
      • Yan L.L.
      • Person S.D.
      • et al.
      Gender differences in the association between sleep duration and body composition: the Cardia Study.
      However, there are few studies examining such differences during adolescence, when such patterns may emerge and crystallize. Identifying the nature of these disparities in adolescence is an important step in designing and implementing prevention efforts, which could circumvent the long-term negative outcomes associated with short sleep duration.
      • Gangwisch J.E.
      • Malaspina D.
      • Babiss L.A.
      • Opler M.G.
      • Posner K.
      • Shen S.
      • et al.
      Short sleep duration as a risk factor for hypercholesterolemia: analyses of the National Longitudinal Study of Adolescent Health.
      • Gangwisch J.E.
      • Heymsfield S.B.
      • Boden-Albala B.
      • Buijs R.M.
      • Kreier F.
      • Pickering T.G.
      • et al.
      Sleep duration as a risk factor for diabetes incidence in a large U.S. sample.
      Adolescence is an important developmental period to examine, as this is a time during which sleep duration on school days significantly decreases.
      • Ohayon M.M.
      • Carskadon M.A.
      • Guilleminault C.
      • Vitiello M.V.
      Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals: developing normative sleep values across the human lifespan.
      To date, the data on sex and racial/ethnic differences in sleep duration in this age range are mixed. One report found that high school girls were more likely than boys (71.9% vs 66.7%, respectively) to sleep less than 8 hours on an average school night.
      • Centers for Disease Control and Prevention
      Youth Risk Behavior Surveillance—United States, 2011.
      Conversely, studies of Turkish children, urban adolescents and high school students found girls slept longer than boys.
      • Arman A.R.
      • Ay P.
      • Fis N.P.
      • Ersu R.
      • Topuzoglu A.
      • Isik U.
      • et al.
      Association of sleep duration with socio-economic status and behavioural problems among schoolchildren.
      • Matthews K.A.
      • Hall M.
      • Dahl R.E.
      Sleep in healthy black and white adolescents.
      • Moore M.
      • Kirchner H.L.
      • Drotar D.
      • Johnson N.
      • Rosen C.
      • Redline S.
      Correlates of adolescent sleep time and variability in sleep time: the role of individual and health related characteristics.
      Still, other studies found no differences between young adolescent (ie, age 11-14 years) or high school (ie, age 14-18 years) boys and girls.
      • Lee K.A.
      • McEnany G.
      • Weekes D.
      Gender differences in sleep patterns for early adolescents.
      • Wolfson A.R.
      • Carskadon M.A.
      Sleep schedules and daytime functioning in adolescents.
      • Yang C.K.
      • Kim J.K.
      • Patel S.R.
      • Lee J.H.
      Age-related changes in sleep/wake patterns among Korean teenagers.
      Limited research exists examining sleep disparities among adolescents of different race/ethnicity groups. Most existing literature examines differences in sleep between African American and White groups and shows that African American students sleep less than White students.
      • Matthews K.A.
      • Hall M.
      • Dahl R.E.
      Sleep in healthy black and white adolescents.
      • Moore M.
      • Kirchner H.L.
      • Drotar D.
      • Johnson N.
      • Rosen C.
      • Redline S.
      Correlates of adolescent sleep time and variability in sleep time: the role of individual and health related characteristics.
      Fewer studies examine sleep disparities in other race/ethnicities. Existing evidence shows that African American and Asian students sleep less than White and Hispanic students,
      • Adam E.K.
      • Snell E.K.
      • Pendry P.
      Sleep timing and quantity in ecological and family context: a nationally representative time-diary study.
      • Reither E.
      • Krueger P.
      • Hale L.
      • Reiter E.
      • Peppard P.
      Ethnic variation in the association between sleep and body mass among US adolescents.
      with mixed results between Hispanic and White children. Although 1 study reported Hispanic children sleep longer than White children,
      • Williams J.A.
      • Zimmerman F.J.
      • Bell J.F.
      Norms and trends of sleep time among US children and adolescents.
      another study reported the opposite but only on the weekends,
      • Adam E.K.
      • Snell E.K.
      • Pendry P.
      Sleep timing and quantity in ecological and family context: a nationally representative time-diary study.
      whereas yet another study reports no differences.
      • Reither E.
      • Krueger P.
      • Hale L.
      • Reiter E.
      • Peppard P.
      Ethnic variation in the association between sleep and body mass among US adolescents.
      The current study adds to this literature by examining sleep duration disparities between African American, White, Hispanic, and Asian students.
      There are several limitations to the existing literature. One limitation is that studies typically use parent-report questionnaires, which may become less accurate as children age and require less oversight by parents.
      • Arman A.R.
      • Ay P.
      • Fis N.P.
      • Ersu R.
      • Topuzoglu A.
      • Isik U.
      • et al.
      Association of sleep duration with socio-economic status and behavioural problems among schoolchildren.
      • Crosby B.
      • LeBourgeois M.K.
      • Harsh J.
      Racial differences in reported napping and nocturnal sleep in 2- to 8-year-old children.
      • Iglowstein I.
      • Jenni O.G.
      • Molinari L.
      • Largo R.H.
      Sleep duration from infancy to adolescence: reference values and generational trends.
      • Laberge L.
      • Petit D.
      • Simard C.
      • Vitaro F.
      • Tremblay R.E.
      • Montplaisir J.
      Development of sleep patterns in early adolescence.
      In addition, age ranges varied across studies (ie, 5-19 years old). This makes it difficult to have confidence in results (eg, 5-year-olds are considerably different from 11- or 19-year-olds) and compare results across studies. The current study examined sex and race/ethnicity differences in child-reported sleep durations in a group of racially/ethnically diverse young adolescents (ie, 11- to 14-year-olds).

      Methods

      Participants

      Young adolescents attending 1 of 6 public middle schools in the Denton Independent School District, in Denton, TX, were recruited for the current study after approval by the University Human Subjects Research Institutional Review Board, the school district administrative offices, and the principals at each of the schools. A total of 1624 participants completed the study. Participants were excluded from the study for not providing sleep duration or race/ethnicity data or for being greater than 14 years old. Finally, 7 participants were excluded based on race/ethnicity criteria because of small cell sizes (ie, 6 American Indian/Alaskan Native and 1 Filipino). After these exclusions, the final sample was 1543 middle school girls (51.1%) and boys (48.9%), between the ages of 11 and 14 (Mean = 12.31; SD = .95). Race/ethnicity characteristics of the final sample included 62.7% White, 23.7% Hispanic/Latino, 10.4% African American, and 3.2% Asian.

      Procedure

      Parental consent and child assent were obtained during school registration, before participation in the study. Students were then asked to complete approximately 30 minutes of questionnaires during their physical education class. Upon completion of the questionnaires, students at each school were entered into a lottery drawing for cash prizes.
      • Petrie T.A.
      • Greenleaf C.
      • Martin S.
      Biopsychosocial and physical correlates of middle school boys’ and girls’ body satisfaction.
      All data collection took place during the regular school year (2010-2011).

      Measures

      Information on the students' race/ethnicity, sex, grade level, and age was provided by the school district. Race/ethnicity categories included American Indian/Alaskan Native, Asian, Native American/Pacific Islander, Filipino, Hispanic/Latino, Black/African American, and White. Information on student-reported sleep duration was obtained by student self-report on the Pittsburgh Sleep Quality Index.
      • Buysse D.J.
      • Reynolds C.F.
      • Monk T.H.
      • Berman S.R.
      • Kupfer D.J.
      Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research.

      Results

      Overall, this sample of young adolescents reportedly slept an average of 8.27 (SD = 1.32) hours per night. Means and SDs for males and females within each race/ethnicity group are reported in the Table. A 2-way univariate analysis of variance was performed with sex and race/ethnicity as the grouping variables and student-reported sleep duration as the outcome variable. The analysis of variance revealed that there was a trend for a significant main effect for sex (P = .067, partial η2 = .002), with boys reporting more sleep than girls. There was a significant main effect for race/ethnicity (P < .001, partial η2 = .012), with Hispanic and African American adolescents reporting significantly shorter sleep duration than Asian and White adolescents.
      TableSleep duration means and SDs for sex and race/ethnicity.
      Race/ethnicitySexTotal
      MaleFemale
      nMean(SD)nMean(SD)nMean(SD)
      Asian298.52
      Represents comparison between Asian and Hispanic males (P= .031).
      (0.87)218.15(1.75)508.37(1.31)
      Hispanic1637.94
      Represents comparison between Asian and Hispanic males (P= .031).
      ,
      Represents comparison between Hispanic and White males (P< .001).
      (1.44)2028.16(1.38)3658.06(1.41)
      African American748.35
      Represents significantly different sex pairwise comparisons within ethnicity (P < .05).
      (1.22)867.80
      Represents comparison between African American and White females (P= .019).
      ,
      Represents significantly different sex pairwise comparisons within ethnicity (P < .05).
      (1.45)1608.05(1.37)
      White4898.44
      Represents comparison between Asian and Hispanic males (P= .031).
      (1.28)4798.30
      Represents comparison between African American and White females (P= .019).
      (1.26)9688.37(1.27)
      Total7558.33(1.31)7888.20(1.34)15438.27(1.32)
      Matching letters represent significantly different ethnicity pairwise comparisons within sex (P < .05).
      a Represents comparison between Asian and Hispanic males (P= .031).
      b Represents comparison between Hispanic and White males (P< .001).
      c Represents comparison between African American and White females (P= .019).
      low asterisk Represents significantly different sex pairwise comparisons within ethnicity (P < .05).
      The results indicate a significant sex × race/ethnicity interaction effect (P = .014, partial η2 = .002). Within males, there was a significant difference between ethnicities (P < .001), with post hoc tests revealing significantly lower sleep durations in Hispanic males (7.95 hours) than both Asian (8.51 hours; P = .031) and White (8.44 hours; P < .001) males, but no differences between African Americans (8.05 hours) and these other race/ethnicities. Within females, there was a significant difference between ethnicities (P = .014), with post hoc tests revealing significantly lower sleep durations in African American females (7.80 hours) than White females (8.30 hours; Ps < .05) but no differences among Asian (8.15 hours) or Hispanic (8.16 hours) females.
      Simple effects testing of sex differences within each race/ethnicity group revealed significant differences between African American (P = .011) males (8.35 hours) and females (7.80 hours) and a similar trend (P = .078) in Whites (males = 8.44 hours, females = 8.30 hours), with no significant sex differences among Asian or Hispanic participants.

      Discussion

      The aim of the current study was to determine if there were sex and race/ethnicity differences in sleep duration in a sample of young adolescents. The adolescents slept an average of 8.27 hours per night as a whole, which is nearly an hour less than the 9.25 hours recommended for adolescents to maintain optimal daytime alertness.
      • Carskadon M.A.
      • Harvey K.
      • Duke P.
      • Anders T.F.
      • Litt I.F.
      • Dement W.C.
      Pubertal changes in daytime sleepiness.
      Hispanic males slept less than Asian and White males, and African American females slept less than White females. African American females slept significantly less than African American males, with a similar trend among Whites.
      With respect to sex differences, the results of the current study supported those of the Centers for Disease Control and Prevention
      • Centers for Disease Control and Prevention
      Youth Risk Behavior Surveillance—United States, 2011.
      study, wherein boys demonstrated significantly longer sleep duration than girls. It is possible that biological and social determinants may be playing a role in the sex differences in sleep duration. For instance, girls enter puberty earlier (10 or 11 years old) than boys (12 years old; American Medical Association, 2001), which could result in sleep period phase delays.
      • Taylor D.J.
      • Jenni O.G.
      • Acebo C.
      • Carskadon M.A.
      Sleep tendency during extended wakefulness: insights into adolescent sleep regulation and behavior.
      • Carskadon M.A.
      • Vieira C.
      • Acebo C.
      Association between puberty and delayed phase preference.
      In addition, females are more likely to text message,
      • Faulkner X.
      • Culwin F.
      When fingers do the talking: a study of text messaging.
      instant message, or use social networking sites
      • Pujazon-Zazik M.
      • Park M.J.
      To tweet, or not to tweet: gender differences and potential positive and negative health outcomes of adolescents' social internet use.
      than males, which commonly happens after lights out
      • Van den Bulck J.
      Adolescent use of mobile phones for calling and for sending text messages after lights out: results from a prospective cohort study with a one-year follow-up.
      and could result in further truncation of sleep time. It is not clear, however, why these differences would have only been present in African American adolescents. One possible explanation may be that African Americans enter puberty earlier than Whites,
      • Styne D.M.
      Puberty, obesity and ethnicity.
      thus potential biological effects on sleep may be more evident in this racial/ethnic group.
      Results were in agreement with those of previous research showing that African Americans have shorter sleep durations than Whites,
      • Durrence H.H.
      • Lichstein K.L.
      The sleep of African Americans: a comparative review.
      • Matthews K.A.
      • Hall M.
      • Dahl R.E.
      Sleep in healthy black and white adolescents.
      • Moore M.
      • Kirchner H.L.
      • Drotar D.
      • Johnson N.
      • Rosen C.
      • Redline S.
      Correlates of adolescent sleep time and variability in sleep time: the role of individual and health related characteristics.
      • Rao U.
      • Hammen C.L.
      • Poland R.E.
      Ethnic differences in electroencephalographic sleep patterns in adolescents.
      but this effect was only significant in females. The findings that, among males, Hispanic students slept less than both Asian and White students were unique. Racial/ethnic differences in adolescent sleep duration may have several explanations. First, these findings may be related to differences in bedtimes, with African American and Hispanic adolescents demonstrating later bedtimes than Whites, which could contribute directly to shorter sleep duration. Second, lower socioeconomic status, a well-known correlate of race/ethnicity, has been linked to shorter sleep duration in adolescents. Both socioeconomic status and race have been linked to increased stress, which has been demonstrated to interfere with sleep.
      • Goodman E.
      • McEwen B.S.
      • Dolan L.M.
      • Schafer-Kalkhoff T.
      • Adler N.E.
      Social disadvantage and adolescent stress.
      However, little is yet known about the potential mechanisms driving the relationship between race/ethnicity and sleep duration in adolescents.
      These results must be interpreted with caution, as participants were from 1 independent school district in North Texas, possibly limiting generalizability. An advantage of this approach was that it controlled for school start times and extracurricular activities, which are standardized across the Denton Independent School District and could have profound effects on sleep time. Future studies should examine sleep duration with a larger sample more representative of the overall population.
      Although this study used self-report rather than parent report, it may still represent a bias, and future studies should examine sleep more objectively. Furthermore, this study only used a single estimate, which may not represent general trends in sleep behavior including: differences across the week, weekdays vs weekends, or differences across weeks and months. Finally, the self-report may not include additional sleep episodes such as naps that may contribute to aggregate sleep over a 24-hour cycle. Prospective studies are needed using more objective measurements of sleep across the 24-hour cycle to validate these results.

      Conclusions

      The current study showed that there are race/ethnicity and sex disparities in self-reported sleep duration that are evident as early as young adolescence (ie, 11-14 years old). Early identification and intervention in middle school with adolescents demonstrating shorter sleep duration could prevent or delay the onset of more serious negative physical health, psychological health, daytime functioning, and academic performance outcomes, which have also been shown to differentially affect race/ethnicity and sex groups.

      Disclosures

      The authors report no disclosures.

      References

        • U.S. Department of Health and Human Services (HHS)
        Office of Disease Prevention and Health Promotion, Healthy People 2020: Rockville, MD.
        • National Partnership for Action to End Health Disparities
        National Stakeholder Strategy for Achieving Health Equity.
        U.S. Department of Health & Human Services, Office of Minority Health, Rockville, MD2011
        • Institute of Medicine
        Unequal treatment: confronting racial and ethnic disparities in health care.
        2002
        • Anderson N.B.
        Behavioral and sociological perspectives on ethnicity and health: introduction to the special issue: American Psychological Association.
        1995
        • Pampel F.C.
        • Krueger P.M.
        • Denney J.T.
        Socioeconomic disparities in health behaviors.
        Annu Rev Sociol. 2010; 36: 349-370
        • Cappuccio F.P.
        • D'Elia L.
        • Strazzullo P.
        • Miller M.A.
        Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies.
        Sleep. 2010; 33: 585-592
        • Cappuccio F.P.
        • D'Elia L.
        • Strazzullo P.
        • Miller M.A.
        Quantity and quality of sleep and incidence of type 2 diabetes a systematic review and meta-analysis.
        Diabetes Care. 2010; 33: 414-420
        • Wang Q.
        • Xi B.
        • Liu M.
        • Zhang Y.
        • Fu M.
        Short sleep duration is associated with hypertension risk among adults: a systematic review and meta-analysis.
        Hypertens Res. 2012; 35: 1012-1018
        • Cappuccio F.P.
        • Cooper D.
        • D'Elia L.
        • Strazzullo P.
        • Miller M.A.
        Sleep duration predicts cardiovascular outcomes: a systematic review and meta-analysis of prospective studies.
        Eur Heart J. 2011; 32: 1484-1492
        • Cappuccio F.P.
        • Taggart F.M.
        • Kandala N.-B.
        • Currie A.
        Meta-analysis of short sleep duration and obesity in children and adults.
        Sleep. 2008; 31: 619-626
        • Chen X.
        • Beydoun M.A.
        • Wang Y.
        Is sleep duration associated with childhood obesity? A systematic review and meta-analysis.
        Obesity. 2008; 16: 265-274
        • Gangwisch J.E.
        • Malaspina D.
        • Babiss L.A.
        • Opler M.G.
        • Posner K.
        • Shen S.
        • et al.
        Short sleep duration as a risk factor for hypercholesterolemia: analyses of the National Longitudinal Study of Adolescent Health.
        Sleep. 2010; 30: 1667-1673
        • Gangwisch J.E.
        • Heymsfield S.B.
        • Boden-Albala B.
        • Buijs R.M.
        • Kreier F.
        • Pickering T.G.
        • et al.
        Sleep duration as a risk factor for diabetes incidence in a large U.S. sample.
        Sleep. 2007; 30: 1667-1673
        • Gallicchio L.
        • Kalesan B.
        Sleep duration and mortality: a systematic review and meta-analysis.
        J Sleep Res. 2009; 18: 148-158
        • Ivanenko A.
        • Crabtree V.M.
        • Gozal D.
        Sleep and depression in children and adolescents.
        Sleep Med Rev. 2005; 9: 115-129
        • Alfano C.A.
        • Zakem A.H.
        • Costa N.M.
        • Taylor L.K.
        • Weems C.F.
        Sleep problems and their relation to cognitive factors, anxiety, and depressive symptoms in children and adolescents.
        Depress Anxiety. 2009; 26: 503-512
        • Gromov I.
        • Gromov D.
        Sleep and substance use and abuse in adolescents.
        Child Adolesc Psychiatr Clin N Am. 2009; 18: 929-946
        • Perez-Lloret S.
        • Videla A.J.
        • Richaudeau A.
        • Vigo D.
        • Rossi M.
        • Cardinali D.P.
        • et al.
        A multi-step pathway connecting short sleep duration to daytime somnolence, reduced attention, and poor academic performance: an exploratory cross-sectional study in teenagers.
        J Clin Sleep Med. 2013; 9: 469-473
        • Beebe D.W.
        • Rose D.
        • Amin R.
        Attention, learning, and arousal of experimentally sleep-restricted adolescents in a simulated classroom.
        J Adolesc Health. 2010; 47: 523-525
        • Perkinson-Gloor N.
        • Lemola S.
        • Grob A.
        Sleep duration, positive attitude toward life, and academic achievement: the role of daytime tiredness, behavioral persistence, and school start times.
        J Adolesc. 2013; 36: 311-318
        • Hale L.
        • Do D.P.
        Racial differences in self-reports of sleep duration in a population-based study.
        Sleep. 2007; 30: 1096-1103
        • Unruh M.L.
        • Redline S.
        • An M.W.
        • Buysse D.J.
        • Nieto F.J.
        • Yeh J.L.
        • et al.
        Subjective and objective sleep quality and aging in the sleep heart health study.
        J Am Geriatr Soc. 2008; 56: 1218-1227
        • Beatty D.L.
        • Hall M.H.
        • Kamarck T.A.
        • Buysse D.J.
        • Owens J.F.
        • Reis S.E.
        • et al.
        Unfair treatment is associated with poor sleep in African American and Caucasian adults: Pittsburgh SleepSCORE project.
        Health Psychol. 2011; 30: 351-359
        • Durrence H.H.
        • Lichstein K.L.
        The sleep of African Americans: a comparative review.
        Behav Sleep Med. 2006; 4: 29-43
        • St-Onge M.P.
        • Perumean-Chaney S.
        • Desmond R.
        • Lewis C.E.
        • Yan L.L.
        • Person S.D.
        • et al.
        Gender differences in the association between sleep duration and body composition: the Cardia Study.
        Int J Endocrinol. 2010; 2010: 726071
        • Ohayon M.M.
        • Carskadon M.A.
        • Guilleminault C.
        • Vitiello M.V.
        Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals: developing normative sleep values across the human lifespan.
        Sleep. 2004; 27: 1255-1274
        • Centers for Disease Control and Prevention
        Youth Risk Behavior Surveillance—United States, 2011.
        U.S. Department of Health and Human Services, Atlanta, GA2012
        • Arman A.R.
        • Ay P.
        • Fis N.P.
        • Ersu R.
        • Topuzoglu A.
        • Isik U.
        • et al.
        Association of sleep duration with socio-economic status and behavioural problems among schoolchildren.
        Acta Paediatr. 2011; 100: 420-424
        • Lee K.A.
        • McEnany G.
        • Weekes D.
        Gender differences in sleep patterns for early adolescents.
        J Adolesc Health. 1999; 24: 16-20
        • Wolfson A.R.
        • Carskadon M.A.
        Sleep schedules and daytime functioning in adolescents.
        Child Dev. 1998; 69: 875-887
        • Yang C.K.
        • Kim J.K.
        • Patel S.R.
        • Lee J.H.
        Age-related changes in sleep/wake patterns among Korean teenagers.
        Pediatrics. 2005; 115: 250-256
        • Matthews K.A.
        • Hall M.
        • Dahl R.E.
        Sleep in healthy black and white adolescents.
        Pediatrics. 2014; 133: e1189-e1196
        • Moore M.
        • Kirchner H.L.
        • Drotar D.
        • Johnson N.
        • Rosen C.
        • Redline S.
        Correlates of adolescent sleep time and variability in sleep time: the role of individual and health related characteristics.
        Sleep Med. 2011; 12: 239-245
        • Adam E.K.
        • Snell E.K.
        • Pendry P.
        Sleep timing and quantity in ecological and family context: a nationally representative time-diary study.
        J Fam Psychol. 2007; 21: 4-19
        • Reither E.
        • Krueger P.
        • Hale L.
        • Reiter E.
        • Peppard P.
        Ethnic variation in the association between sleep and body mass among US adolescents.
        Int J Obes. 2014; 38: 944-999
        • Williams J.A.
        • Zimmerman F.J.
        • Bell J.F.
        Norms and trends of sleep time among US children and adolescents.
        JAMA Pediatrics. 2013; 167: 55-60
        • Crosby B.
        • LeBourgeois M.K.
        • Harsh J.
        Racial differences in reported napping and nocturnal sleep in 2- to 8-year-old children.
        Pediatrics. 2005; 115: 225-232
        • Iglowstein I.
        • Jenni O.G.
        • Molinari L.
        • Largo R.H.
        Sleep duration from infancy to adolescence: reference values and generational trends.
        Pediatrics. 2003; 111: 302-307
        • Laberge L.
        • Petit D.
        • Simard C.
        • Vitaro F.
        • Tremblay R.E.
        • Montplaisir J.
        Development of sleep patterns in early adolescence.
        J Sleep Res. 2011; 10: 59-67
        • Petrie T.A.
        • Greenleaf C.
        • Martin S.
        Biopsychosocial and physical correlates of middle school boys’ and girls’ body satisfaction.
        Sex Roles. 2010; 63: 631-644
        • Buysse D.J.
        • Reynolds C.F.
        • Monk T.H.
        • Berman S.R.
        • Kupfer D.J.
        Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research.
        Psychiatry Res. 1989; 28: 193-213
        • Carskadon M.A.
        • Harvey K.
        • Duke P.
        • Anders T.F.
        • Litt I.F.
        • Dement W.C.
        Pubertal changes in daytime sleepiness.
        Sleep. 1980; 25: 453-460
        • Taylor D.J.
        • Jenni O.G.
        • Acebo C.
        • Carskadon M.A.
        Sleep tendency during extended wakefulness: insights into adolescent sleep regulation and behavior.
        J Sleep Res. 2005; 14: 239-244
        • Carskadon M.A.
        • Vieira C.
        • Acebo C.
        Association between puberty and delayed phase preference.
        Sleep. 1993; 16: 258-262
        • Faulkner X.
        • Culwin F.
        When fingers do the talking: a study of text messaging.
        Interact Comput. 2005; 17: 167-185
        • Pujazon-Zazik M.
        • Park M.J.
        To tweet, or not to tweet: gender differences and potential positive and negative health outcomes of adolescents' social internet use.
        Am J Mens Health. 2010; 4: 77-85
        • Van den Bulck J.
        Adolescent use of mobile phones for calling and for sending text messages after lights out: results from a prospective cohort study with a one-year follow-up.
        Sleep. 2007; 30: 1220-1223
        • Styne D.M.
        Puberty, obesity and ethnicity.
        Trends Endocrinol Metab. 2004; 15: 472-478
        • Rao U.
        • Hammen C.L.
        • Poland R.E.
        Ethnic differences in electroencephalographic sleep patterns in adolescents.
        Asian J Psychiatry. 2009; 2: 17-24
        • Goodman E.
        • McEwen B.S.
        • Dolan L.M.
        • Schafer-Kalkhoff T.
        • Adler N.E.
        Social disadvantage and adolescent stress.
        J Adolesc Health. 2005; 37: 484-492