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Adolescents and Emerging Adults' Sleep Patterns: New Developments

      See Related Articles pgs. 124 and 133
      Over the last three decades, researchers have established an increasingly more nuanced understanding of adolescents' sleep demands, circadian timing, underlying bioregulatory processes, and environmental constraints [
      • Carskadon M.A.
      The second decade.
      ,
      • Carskadon M.A.
      • Harvey K.
      • Duke P.
      • et al.
      Pubertal changes in daytime sleepiness.
      ,
      • Carskadon M.A.
      • Acebo C.
      Regulation of sleepiness in adolescents: update, insights, and speculation.
      ,
      • Carskadon M.A.
      • Acebo C.
      • Jenni O.G.
      Regulation of adolescent sleep: implications for behavior.
      ,
      • Crowley S.J.
      • Acebo C.
      • Carskadon M.A.
      Sleep, circadian rhythms, and delayed phase in adolescence.
      ]. Studies have also documented the clear consequences of insufficient and inconsistent sleep for developing adolescents, such as poor academic performance and school absenteeism, drowsy-driving accidents, substance abuse, and emotion regulation difficulties [
      • Danner F.
      • Phillips B.
      Adolescent sleep, school start times, and teen motor vehicle crashes.
      ,
      • Hardway C.
      • Fuligni A.J.
      Dimensions of family connectedness among adolescents with Mexican, Chinese, and European backgrounds.
      ,
      • Johnson E.O.
      • Breslau N.
      Sleep problems and substance use in adolescence.
      ,
      • Wolfson A.R.
      • Carskadon M.C.
      Understanding adolescents' sleep patterns and school performance: A critical appraisal.
      ,
      • Wolfson A.R.
      • Armitage R.
      Sleep and its relation to adolescent depression.
      ]. This critical area of adolescent health research has also started to inform policy from school start times to drivers' education programs [
      • Moore R.T.
      • Kaprielian R.
      • Auerbach J.
      Asleep at the Wheel: Report of the Special Commission on Drowsy Driving.
      ,
      • O'Malley E.B.
      • O'Malley M.B.
      School start time and its impact on learning and behavior.
      ,
      • Wolfson A.R.
      • Spaulding N.
      • Dandrow C.
      • Baroni E.
      Early versus late starting middle schools: The importance of a good night's sleep for young adolescents.
      ,
      • Wolfson A.R.
      • Carskadon M.A.
      A survey of factors influencing school start times.
      ,
      • Wahlstrom K.
      Accommodating the sleep patterns of adolescents within current educational structures: An uncharted path.
      ]. Yet, at this juncture, additional and new questions arise. In this issue of the Journal of Adolescent Health, researchers investigate two understudied areas—predictors of sleep difficulties in older adolescents or emerging adults, and teenage athletes' sleep patterns and daytime functioning [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ,
      • Brand S
      • Gerber M
      • Beck J
      • et al.
      High exercise levels are related to favorable sleep patterns and psychological functioning in adolescents: A comparison of athletes and controls.
      ].
      As Lund et al point out, few carefully designed studies have captured and articulated college-age adolescents or emerging adults' changing sleep patterns [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ]. The end of adolescence is defined and/or measured by a complexity of physical, psychological, social, and cognitive measures. One developmental aspect of adolescence involves the capacity to stay up late and to sleep in or delay wake time. Roenneberg et al queried a large sample of 8–90-year olds regarding their sleep/wake schedules and calculated the average “mid-point” of each person's sleep duration, or the time half way between when they go to sleep and when they wake up [
      • Roennberg T.
      • Kuehnle T.
      • Pramstaller P.
      • et al.
      A marker for the end of adolescence.
      ]. They found that children and adolescents slept increasingly later until the age of approximately 20, when there is an abrupt shift in sleep schedules. After age 20, Roenneberg et al found that the mid-point times became increasingly earlier again [
      • Roennberg T.
      • Kuehnle T.
      • Pramstaller P.
      • et al.
      A marker for the end of adolescence.
      ]. Although this is cross-sectional data, it suggests that the timing of sleep changes over the course of emerging adulthood.
      A small number of studies have examined sleep/wake patterns over the transition from high school to college. In a brief report, Carskadon and Davis surveyed close to 1000 undergraduate students in the spring before entering college, and again during the first fall semester [
      • Carskadon M.A.
      • Davis S.S.
      Sleep-wake patterns in the high-school-to-college transition: Preliminary data.
      ]. These preliminary findings showed a significant pattern of sleeping less and delaying nighttime sleep by about 2 hours across the transition to college. Pilcher et al documented that sleep habits are one of the first daily habits to change for first-year college students, and other studies found that college students, in general, exhibit irregular sleep-wake cycles with bedtime delays on weekends and short sleep durations on weekdays [
      • Pilcher J.J.
      • Ginter D.R.
      • Sadowsky B.
      Sleep quality versus sleep quantity: Relationships between sleep and measures of health, well-being and sleepiness in college students.
      ,
      • Lack L.C.
      Delayed sleep and sleep loss in university students.
      ,
      • Hawkins J.
      • Shaw P.
      Self-reported sleep quality in college students: A repeated measures approach.
      ,
      • Valdez P.
      • Ramirez C.
      • Garcia A.
      Delaying and extending sleep during weekends: Sleep recovery or circadian effects.
      ]. Moreover, college students today are getting less sleep than students in the past, and a high proportion of students suffer from a number of sleep problems. National surveys of undergraduates, for example, have shown a steady decline in median hours of sleep reported: from 7.75 in 1969 to 6.65 in 2001, with first and second year students reporting less time in bed because of earlier wake times and more erratic sleep-wake schedules [
      • Hicks R.A.
      • Fernandez C.
      • Pellegrini R.J.
      The changing sleep habits of university students: An update.
      ,
      • Singleton R.A.
      • Wolfson A.R.
      Alcohol consumption, sleep, and academic performance among college students.
      ,
      • Tsai L.L.
      • Li S.P.
      Sleep patterns in college students gender and grade differences.
      ]. In addition, in recent surveys nearly 75% of college students reported occasional sleep problems such as difficulty falling asleep, sleep disturbances, delayed sleep phase syndrome, and excessive daytime sleepiness [
      • Brown F.C.
      • Buboltz W.J.
      • Soper B.
      Prevalence of delayed sleep phase syndrome in university students.
      ,
      • Buboltz Jr., W.C.
      • Brown F.
      • Soper B.
      Sleep habits and patterns of college students: A preliminary study.
      ,
      • Ohayon M.M.
      • Roberts R.E.
      Comparability of sleep disorders diagnoses using DSM-IV and ICSD classifications with adolescents.
      ].
      Just over a decade ago, the National Institutes of Health recognized adolescents and emerging adults (ages: 12–25 years) as a population at high risk for problem sleepiness based on “evidence that the prevalence of problem sleepiness is high and increasing with particularly serious consequences” [
      National Institutes of Health
      National Center on Sleep Disorders Research and Office of Prevention, Education, and Control. Working Group Report on Problem Sleepiness.
      ].However, relatively little systematic sleep research has focused on this critical developmental time-emerging adulthood.
      A well-designed study of over 1000 undergraduates' sleep-wake patterns and emotional well being by Lund et al helps fill in some of the gaps in our knowledge, regarding emerging adults' sleep and daytime functioning [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ]. First, their results demonstrate that the serious problem of insufficient and erratic sleep in middle and high school age adolescents does not come to an end with graduation, but continues into the college or emerging young adult years [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ]. Second, in comparing their first-year college students to the high school students surveyed in the 2006 National Sleep Foundation Sleep in America Poll or other previous studies of high school age adolescents, weeknight bedtimes and rise times appeared to be 1 hour 15 minutes later [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ,
      National Sleep Foundation
      Sleep in America Poll.
      ,
      • Wolfson A.R.
      • Carskadon M.A.
      Sleep schedules and daytime functioning in adolescents.
      ]. Yet, first year students had significantly later bed and rise times than older third and fourth-year college students [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ]. This is a striking finding as it is in keeping with Roenneberg's work described earlier. After age 20, Roenneberg et al found that mid-point times became increasingly earlier again; in other words, sleep schedules seem to become increasingly more delayed over the course of adolescence, yet this pattern seems to change by the third or fourth year of college—which generally corresponds to about ages 20–22 [
      • Roennberg T.
      • Kuehnle T.
      • Pramstaller P.
      • et al.
      A marker for the end of adolescence.
      ]. These striking cross-sectional findings suggest a developmental change; however, they clearly need to be examined further, using a longitudinal study design and more objective measures such as polysomnography, actigraphy, salivary melatonin. Third, Lund et al evaluated the factors that might predict sleep quality in this sample of college students, using measures of mood, perceived distress, and substance use [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ]. As the authors discuss themselves, college students overwhelmingly reported that academic and emotional stress were significantly associated with poor sleep quality. Perceived stress accounted for significantly more of an impact on sleep than caffeine and alcohol use, exercise frequency, or computer/television use. Other studies have found that insufficient sleep and poor sleep quality are associated with stress, negative mood, and difficulties with stress management [
      • Wolfson A.R.
      • Carskadon M.A.
      Sleep schedules and daytime functioning in adolescents.
      ,
      • Carney C.E.
      • Edinger J.D.
      • Meyer B.
      • et al.
      Symptom focused rumination and sleep disturbance.
      ,
      • El-Sheikh M.
      • Buckhalt J.A.
      • Keller P.S.
      • et al.
      Children's objective and subjective sleep disruptions: Links with afternoon cortisol levels.
      ,
      • Gray E.K.
      • Watson D.
      General and specific traits of personality and their relation to sleep and academic performance.
      ]. The transition to college may be particularly stressful for emerging adults, and developing sleep patterns may be one of the first daily habits to change for many first-year college students [
      • Tsai L.L.
      • Li S.P.
      Sleep patterns in college students gender and grade differences.
      ,
      • Hicks T.
      • Heastie S.
      High school to college transition: A profile of the stressors, physical and psychological health issues that affect the first-year on-campus college student.
      ]. As Lund et al point out in the discussion of their findings, the stressors of the college years, particularly early on, may serve as “predisposing, precipitating, and perpetuating factors” for sleep problems at a time when stable, less delayed sleep-wake schedules are still emerging [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ].
      The other study published in the current issue of this Journal examines a countermeasure to stress for adolescents—exercise [
      • Brand S
      • Gerber M
      • Beck J
      • et al.
      High exercise levels are related to favorable sleep patterns and psychological functioning in adolescents: A comparison of athletes and controls.
      ]. As the authors note, exercise and/or sports participation are often positively connected to psychosocial well being and stress reduction in adults, as well as adolescents [
      • Norris R.
      • Carroll D.
      • Cochrane R.
      The effects of physical activity and exercise training on psychological stress and well-being in an adolescent population.
      ,
      • Penedo F.J.
      • Dahn J.R.
      Exercise and well-being: A review of mental and physical health benefits associated with physical activity.
      ,
      • Steptoe A.
      • Butler N.
      Sports participation and emotional well being in adolescents.
      ]. Likewise, in Driver and Taylor's review, they argue that although only moderate effect sizes have been noted, meta-analyses demonstrate that exercise increases total sleep time, delays rapid eye movement onset, increases slow-wave sleep, and reduces rapid eye movement sleep [
      • Driver H.S.
      • Taylor S.R.
      Exercise and sleep.
      ]. The sleep-promoting efficacy of exercise in adults or adolescents, however, has yet to be established. Brand et al compared 258 high school-age, Olympic-quality athletes, with 176 controls on their sleep patterns, exercise, and psychological well being, using prospective logs and self-report questionnaires [
      • Brand S
      • Gerber M
      • Beck J
      • et al.
      High exercise levels are related to favorable sleep patterns and psychological functioning in adolescents: A comparison of athletes and controls.
      ]. The adolescent athletes reported healthier sleep quality, shorter sleep latencies, fewer nighttime awakenings, less daytime sleepiness, and better concentration in comparison to the controls. In addition, the athlete group experienced less anxiety and depressed mood [
      • Brand S
      • Gerber M
      • Beck J
      • et al.
      High exercise levels are related to favorable sleep patterns and psychological functioning in adolescents: A comparison of athletes and controls.
      ].
      In keeping with Lund et al, Brand et al findings indicate that being an athlete who exercises regularly and, as a result, reports lower levels of anxiety and stress, seems to predict higher quality sleep-wake patterns and less daytime sleepiness [
      • Lund HG
      • Reider BD
      • Whiting AB
      • Prichard JR
      Sleep patterns and predictors of disturbed sleep in a large population of college students.
      ,
      • Brand S
      • Gerber M
      • Beck J
      • et al.
      High exercise levels are related to favorable sleep patterns and psychological functioning in adolescents: A comparison of athletes and controls.
      ]. Both of these timely studies highlight the important stress-coping-sleep relationship for high-school and college-age adolescents. As these two research groups suggest, however, it is still unclear as to how stress is related to sleep and why significant exercise might be beneficial to an adolescent's sleep. For example, in the case of stress, sleep restriction and poor sleep quality appear to be associated with increased cortisol levels [
      • Adam K.
      • Tomney M.
      • Oswald I.
      Physiological and psychological differences between good and poor sleepers.
      ,
      • Steiger A.
      Sleep and the hypothalamo-pituitary-adrenocortical system.
      ]. In particular, the overactivation of the hypothalamic-pituitary-adrenal axis may represent a negative means of coping with stress, which may explain sleep disruptions and irregular sleep patterns, perhaps because allostatic load may prevent adaptive sleep regulation [
      • El-Sheikh M.
      • Buckhalt J.A.
      • Keller P.S.
      • et al.
      Children's objective and subjective sleep disruptions: Links with afternoon cortisol levels.
      ,
      • Steiger A.
      Sleep and the hypothalamo-pituitary-adrenocortical system.
      ]. Adolescents with increased sleep disruptions, shorter sleep duration, later bedtimes, and poorer sleep quality have higher levels of afternoon cortisol and exaggerated cortisol responses to acute lab stressors compared to those with better sleep patterns [
      • El-Sheikh M.
      • Buckhalt J.A.
      • Keller P.S.
      • et al.
      Children's objective and subjective sleep disruptions: Links with afternoon cortisol levels.
      ,
      • Capaldi V.F.
      • Handwerger K.
      • Richardson E.
      • Stroud R.
      Associations between sleep and cortisol responses to stress in children and adolescents: A pilot study.
      ]. Few studies have examined the relationship between actigraphically estimated sleep patterns and cortisol in college students, a particularly stressful developmental period where sleep requirements are often not met. In fact, in recent pilot data from our laboratory, we found that inadequate actigraphically estimated sleep, delayed schedules, and weekly irregularity were connected to higher salivary cortisol levels [

      Azuaje A, Wolfson AR, Ludden AB, et al. Associations between actigraphically estimated sleep and salivary cortisol in college students. Presented at: Society for Research on Adolescence (SRA) Biennial Meeting, 2010, Philadelphia, PA.

      ]. Less desirable health behaviors, such as insufficient sleep, may alter emerging adults' stress response, or lead to increased cortisol output, which may be associated with sleep-wake dysregulation.
      Coming from different angles, both of these studies point out that the relationship between stress, coping strategies, and sleep remains unclear and may be crucial to understanding how older adolescents successfully regulate their sleep/wake patterns over the emerging adulthood transition. On the one hand, stress may alter sleep, yet sleep may represent an attempt to counteract the negative effect of stress [
      • Rothenberg V.
      Stress and sleep.
      ]. Furthermore, health-coping strategies, such as exercise, may mediate the stress-sleep relationship. Finally, researchers, educators, and health care providers need to better understand the developmental trajectory of sleep and circadian timing over the late adolescence-emerging adulthood years.

      References

        • Carskadon M.A.
        The second decade.
        in: Guilleminault C. Sleeping and Waking Disorders: Indications and Techniques. Addison-Wesley, Menlo Park, CA1982: 99-125
        • Carskadon M.A.
        • Harvey K.
        • Duke P.
        • et al.
        Pubertal changes in daytime sleepiness.
        Sleep. 1980; 2: 453-460
        • Carskadon M.A.
        • Acebo C.
        Regulation of sleepiness in adolescents: update, insights, and speculation.
        Sleep. 2002; 25: 606-614
        • Carskadon M.A.
        • Acebo C.
        • Jenni O.G.
        Regulation of adolescent sleep: implications for behavior.
        Ann NY Acad Sci. 2004; 1021: 276-291
        • Crowley S.J.
        • Acebo C.
        • Carskadon M.A.
        Sleep, circadian rhythms, and delayed phase in adolescence.
        Sleep Med. 2007; 8: 602-612
        • Danner F.
        • Phillips B.
        Adolescent sleep, school start times, and teen motor vehicle crashes.
        J Clin Sleep Med. 2008; 4: 533-535
        • Hardway C.
        • Fuligni A.J.
        Dimensions of family connectedness among adolescents with Mexican, Chinese, and European backgrounds.
        Dev Psychol. 2006; 42: 1246-1258
        • Johnson E.O.
        • Breslau N.
        Sleep problems and substance use in adolescence.
        Drug Alcohol Depend. 2001; 64: 1-7
        • Wolfson A.R.
        • Carskadon M.C.
        Understanding adolescents' sleep patterns and school performance: A critical appraisal.
        Sleep Med Rev. 2003; 7: 491-506
        • Wolfson A.R.
        • Armitage R.
        Sleep and its relation to adolescent depression.
        in: Nolen-Hoeksema S. Hilt L.M. Handbook of Depression in Adolescents. Erlbaum, 2008: 279-302
        • Moore R.T.
        • Kaprielian R.
        • Auerbach J.
        Asleep at the Wheel: Report of the Special Commission on Drowsy Driving.
        Massachusetts Prevent Injuries NOW! Network and Special Commission on Drowsy Driving, Boston, MA2009
        • O'Malley E.B.
        • O'Malley M.B.
        School start time and its impact on learning and behavior.
        in: Ivanenko A. Sleep and Psychiatric Disorders in Children and Adolescents. Informa Healthcare, New York, NY2008: 79-94
        • Wolfson A.R.
        • Spaulding N.
        • Dandrow C.
        • Baroni E.
        Early versus late starting middle schools: The importance of a good night's sleep for young adolescents.
        Behav Sleep Med. 2007; 5: 194-209
        • Wolfson A.R.
        • Carskadon M.A.
        A survey of factors influencing school start times.
        NASSP Bull. 2005; 89: 47-64
        • Wahlstrom K.
        Accommodating the sleep patterns of adolescents within current educational structures: An uncharted path.
        in: Carskadon M. Adolescent Sleep Patterns: Biological, Social, and Psychological Influences. Cambridge University Press, Cambridge, UK2002: 172-197
        • Lund HG
        • Reider BD
        • Whiting AB
        • Prichard JR
        Sleep patterns and predictors of disturbed sleep in a large population of college students.
        J Adolesc Health. 2010; 46: 124-132
        • Brand S
        • Gerber M
        • Beck J
        • et al.
        High exercise levels are related to favorable sleep patterns and psychological functioning in adolescents: A comparison of athletes and controls.
        J Adolesc Health. 2010; 46: 133-141
        • Roennberg T.
        • Kuehnle T.
        • Pramstaller P.
        • et al.
        A marker for the end of adolescence.
        Curr Biol. 2004; 14: R1038-R1039
        • Carskadon M.A.
        • Davis S.S.
        Sleep-wake patterns in the high-school-to-college transition: Preliminary data.
        Sleep Res. 1989; 18: 113
        • Pilcher J.J.
        • Ginter D.R.
        • Sadowsky B.
        Sleep quality versus sleep quantity: Relationships between sleep and measures of health, well-being and sleepiness in college students.
        J Psychosom Res. 1997; 42: 583-596
        • Lack L.C.
        Delayed sleep and sleep loss in university students.
        J Am Coll Health. 1986; 35: 105-110
        • Hawkins J.
        • Shaw P.
        Self-reported sleep quality in college students: A repeated measures approach.
        Sleep. 1992; 15: 545-549
        • Valdez P.
        • Ramirez C.
        • Garcia A.
        Delaying and extending sleep during weekends: Sleep recovery or circadian effects.
        Chronobiol Int. 1996; 13: 191-198
        • Hicks R.A.
        • Fernandez C.
        • Pellegrini R.J.
        The changing sleep habits of university students: An update.
        Percept Mot Skills. 2001; 93: 648
        • Singleton R.A.
        • Wolfson A.R.
        Alcohol consumption, sleep, and academic performance among college students.
        J Stud Alcohol Drugs. 2009; 70: 355-363
        • Tsai L.L.
        • Li S.P.
        Sleep patterns in college students gender and grade differences.
        J Psychosom Res. 2004; 56: 231-237
        • Brown F.C.
        • Buboltz W.J.
        • Soper B.
        Prevalence of delayed sleep phase syndrome in university students.
        Coll Stud J. 2001; 35: 472-476
        • Buboltz Jr., W.C.
        • Brown F.
        • Soper B.
        Sleep habits and patterns of college students: A preliminary study.
        J Am Coll Health. 2001; 50: 131-135
        • Ohayon M.M.
        • Roberts R.E.
        Comparability of sleep disorders diagnoses using DSM-IV and ICSD classifications with adolescents.
        Sleep. 2001; 24: 920-925
        • National Institutes of Health
        National Center on Sleep Disorders Research and Office of Prevention, Education, and Control. Working Group Report on Problem Sleepiness.
        National Institutes of Health, Bethseda, MA1997
        • National Sleep Foundation
        Sleep in America Poll.
        National Sleep Foundation, Washington, DC2006
        • Wolfson A.R.
        • Carskadon M.A.
        Sleep schedules and daytime functioning in adolescents.
        Child Dev. 1998; 69: 875-887
        • Carney C.E.
        • Edinger J.D.
        • Meyer B.
        • et al.
        Symptom focused rumination and sleep disturbance.
        Behav Sleep Med. 2006; 4: 228-241
        • El-Sheikh M.
        • Buckhalt J.A.
        • Keller P.S.
        • et al.
        Children's objective and subjective sleep disruptions: Links with afternoon cortisol levels.
        Health Psychol. 2008; 27: 26-33
        • Gray E.K.
        • Watson D.
        General and specific traits of personality and their relation to sleep and academic performance.
        J Pers. 2002; 70: 177-206
        • Hicks T.
        • Heastie S.
        High school to college transition: A profile of the stressors, physical and psychological health issues that affect the first-year on-campus college student.
        J Cult Divers. 2008; 15: 143-147
        • Norris R.
        • Carroll D.
        • Cochrane R.
        The effects of physical activity and exercise training on psychological stress and well-being in an adolescent population.
        J Psychosom Res. 1992; 36: 55-65
        • Penedo F.J.
        • Dahn J.R.
        Exercise and well-being: A review of mental and physical health benefits associated with physical activity.
        Curr Opin Psychiatry. 2005; 18: 189-193
        • Steptoe A.
        • Butler N.
        Sports participation and emotional well being in adolescents.
        Lancet. 1996; 347: 1789-1792
        • Driver H.S.
        • Taylor S.R.
        Exercise and sleep.
        Sleep Med Rev. 2000; 4: 387-402
        • Adam K.
        • Tomney M.
        • Oswald I.
        Physiological and psychological differences between good and poor sleepers.
        J Psychiatr Res. 1986; 20: 301-316
        • Steiger A.
        Sleep and the hypothalamo-pituitary-adrenocortical system.
        Sleep Med Rev. 2002; 6: 125-138
        • Capaldi V.F.
        • Handwerger K.
        • Richardson E.
        • Stroud R.
        Associations between sleep and cortisol responses to stress in children and adolescents: A pilot study.
        Behav Sleep Med. 2005; 3: 177-192
      1. Azuaje A, Wolfson AR, Ludden AB, et al. Associations between actigraphically estimated sleep and salivary cortisol in college students. Presented at: Society for Research on Adolescence (SRA) Biennial Meeting, 2010, Philadelphia, PA.

        • Rothenberg V.
        Stress and sleep.
        in: Pandi-Perumal S.R. Ruoti R.R. Kramer M. Sleep and Psychosomatic Medicine. Andover, Hampshire: Informa Healthcare, 2007: 207-218

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