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Why Do Teens Sleep Too Little? Biology and Society 

Why Do Teens Sleep Too Little? Biology and Society . Mary A. Carskadon, PhD Sleep for Science Research Lab EP Bradley Hospital Alpert Medical School of Brown University Providence, RI. Overview. Examine adolescent sleep behavior Review developmental changes of sleep-wake regulation

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Why Do Teens Sleep Too Little? Biology and Society 

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  1. Why Do Teens Sleep Too Little? Biology and Society  Mary A. Carskadon, PhD Sleep for Science Research Lab EP Bradley Hospital Alpert Medical School of Brown University Providence, RI

  2. Overview • Examine adolescent sleep behavior • Review developmental changes of sleep-wake regulation • Identify other factors that constrain teen sleep • Introduce some behavioral challenges of insufficient sleep

  3. Adolescent Sleep Behavior • Bedtime becomes later • Rise time becomes earlier (school dependent) • Total amount of sleep is reduced

  4. Adolescent Sleep Behavior 8.3 7.6 6.6 5.4 National Sleep Foundation, Sleep in America Poll, 2006

  5. Adolescent Sleep Behavior 8.3 7.6 6.6 5.4 National Sleep Foundation, Sleep in America Poll, 2006

  6. Adolescent Sleep Behavior National Sleep Foundation, Sleep in America Poll, 2006

  7. Adolescent Sleep Behavior National Sleep Foundation, Sleep in America Poll, 2006

  8. Adolescent Sleep Behavior 2242 2312 0000 0054 National Sleep Foundation, Sleep in America Poll, 2006 Yang et al., Pediatrics, 2005 (Korean Teens)

  9. Adolescent Sleep Behavior 0718 0700 0648 0618 National Sleep Foundation, Sleep in America Poll, 2006 Yang et al., Pediatrics, 2005 (Korean Teens)

  10. Adolescent Sleep Behavior 8.3 7.6 6.6 5.4 National Sleep Foundation, Sleep in America Poll, 2006 Yang et al., Pediatrics, 2005 (Korean Teens)

  11. How much sleep do adolescents need? • Converging evidence indicates that optimal sleep for the average adolescent may be 9+ hours • National Sleep Foundation borderline sleep = 8-9 hours

  12. Discrepancy Adolescent sleep need, therefore, does not appear to parallel sleep obtained for many teens.

  13. Factors that Underlie the Discrepancy • Developmental changes in sleep regulation • Circadian timing system • Sleep wake homeostasis • Developmental changes in psychosocial context • Parents and schools

  14. Two-Process Model of Sleep Regulation (Borbély, 1982) • Process C: Circadian Rhythm • Process S: Sleep/Wake Homeostasis (sleep pressure) Borbély & Achermann, 2000

  15. What developmental changes occur to the circadian timing system?

  16. Circadian Regulation Changes: Measures to Assess Process C

  17. Circadian Regulation Changes: Measures to Assess Process C • Phase preference—when do you prefer to be active, sleeping, etc?

  18. Circadian Regulation Changes: Measures to Assess Process C • Phase preference—when do you prefer to be active, sleeping, etc? • Phase of circadian rhythms—what time is it in your brain?

  19. Circadian Regulation Changes: Measures to Assess Process C • Phase preference—when do you prefer to be active, sleeping, etc? • Phase of circadian rhythms—what time is it in your brain? • Period of the circadian timing system—what is the internal day length?

  20. Circadian Regulation Changes: Measures to Assess Process C • Phase preference—when do you prefer to be active, sleeping, etc? • Phase of circadian rhythms—what time is it in your brain? • Period of the circadian timing system—what is the internal day length? • Phase response to light—does light work the same across adolescence?

  21. Animals with Adolescent Phase Delay • Homo sapiens (humans) • Macca mulatta (Rhesus monkeys) • Octodon degus (degu) [some ?] • Rattus norvegicus (laboratory rat) • Mus musculus (laboratory mouse) • Psammomys obesus (fat sand rat) Hagenauer et al., Devel Neurosci, 2009

  22. Phase Delay in Adolescent Humans • Chronotype • Circadian phase

  23. Chronotype and Adolescence • European sample • Time of midsleep on “free” days • Delay is marked across the 2nd decade • Is the inflection a “biological marker for the end of adolesence?” Roenneberg et al., Current Biol., 2004

  24. Melatonin Onset (DLMO) Phase and Puberty Stage Carskadon et al. NYAS, 2004

  25. What might cause phase delay?

  26. What might cause phase delay? • Changes in light exposure • Staying up later // more late light • Waking up later // less morning light

  27. What might cause phase delay? • Changes in light exposure • Staying up later // more late light • Waking up later // less morning light • Change in phase-dependent sensitivity to light exposure

  28. What might cause phase delay? • Changes in light exposure • Staying up later // more late light • Waking up later // less morning light • Change in phase-dependent sensitivity to light exposure • Lengthening of intrinsic circadian period (i.e., longer internal day length)

  29. Exaggerated phase delay to light in pubertal female mice Hagenauer et al., Devel Neurosci, 2001; after Weinert & Kompaeurova, Zoology, 1998

  30. Intrinsic Circadian Period: Adolescents vs. Adults Carskadon & Acebo Sleep, 2005

  31. Circadian Rhythms Summary

  32. Circadian Rhythms Summary • Phase delays during adolescence • Phase preference is later • Melatonin phase is later

  33. Circadian Rhythms Summary • Phase delays during adolescence • Phase preference is later • Melatonin phase is later • Phase-dependent light sensitivity may change

  34. Circadian Rhythms Summary • Phase delays during adolescence • Phase preference is later • Melatonin phase is later • Phase-dependent light sensitivity may change • Intrinsic period may lengthen

  35. Circadian Rhythms Summary • Phase delays during adolescence • Phase preference is later • Melatonin phase is later • Phase-dependent light sensitivity may change • Intrinsic period may lengthen • Result: Late nights are favored (so, too, late mornings)

  36. What developmental changes occur to the sleep-wake homeostasis (sleep pressure) system?

  37. The “look” of sleep changes Tarokh & Carskadon, Encyclopedia of Neuroscience, 2009

  38. Measures of Process S

  39. Measures of Process S • Slow wave (NREM stages 3+4) sleep [qualitative: Deep sleep]

  40. Measures of Process S • Slow wave (NREM stages 3+4) sleep [qualitative: Deep sleep] • Slow-wave activity (SWA) in sleep [quantitative: Slow EEG waves]

  41. Measures of Process S • Slow wave (NREM stages 3+4) sleep [qualitative: Deep sleep] • Slow-wave activity (SWA) in sleep [quantitative: Slow EEG waves] • Sleep propensity (speed of falling asleep)

  42. Changes of Slow Wave Sleep and Slow Wave Activity (SWA) Jenni & Carskadon, Sleep, 2004

  43. Changes of Slow Wave Sleep and Slow Wave Activity (SWA) Jenni & Carskadon, Sleep, 2004

  44. Changes of Slow Wave Sleep and Slow Wave Activity (SWA) Jenni & Carskadon, Sleep, 2004

  45. 7.7 h 3.0 h 13.5 h 2.9 h Across pubertal development, SWA accumulation rate changes Tanner Stages 1/2 Tanner Stage 5 Jenni, Achermann & Carskadon Sleep, 2005

  46. 7.7 h 3.0 h 13.5 h 2.9 h td = 2.8 h Decay Time Constant td = 2.7 h Across pubertal development, SWA accumulation rate changes Tanner Stages 1/2 Tanner Stage 5 Jenni, Achermann & Carskadon Sleep, 2005

  47. 7.7 h 3.0 h 13.5 h 2.9 h td = 2.8 h Decay Time Constant td = 2.7 h ti = 8.9 h Rise Time Constant ti = 12.1 h Across pubertal development, SWA accumulation rate changes Tanner Stages 1/2 Tanner Stage 5 Jenni, Achermann & Carskadon Sleep, 2005

  48. Model of Process S in Development Jenni & LeBourgeois Curr Op Psychiatry, 2006

  49. Response to extended wakefulness during pubertal development 2.5 6.5 10.5 14.5 18.5 22.5 26.5 Hours Awake Taylor et al., J Sleep Res, 2005

  50. Response to extended wakefulness during pubertal development 2.5 6.5 10.5 14.5 18.5 22.5 26.5 Hours Awake Taylor et al., J Sleep Res, 2005

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