American Academy of Child & Adolescent Psychiatry.

American Academy of Family Physicians.

American Council on Exercise.

American Psychological Association.

Andrade, J. Applied Cognitive Psychology, January 2010; vol 24: pp 100-106.

Baumeister, R.F. Social Psychology and Human Nature, Cengage Learning, 2007.

Carpenter, S. Monitor on Psychology, October 2001; vol 32: pp 42.

Carter, M. Journal of Adolescence, February 2007; vol 30: pp 51-62.

Center for Young Women's Health.

Children, Youth, and Women's Health Service.

Clift, S. Proceedings of the International Symposium on Performance Science 2007, pp 201-207.

Columbia University.

Connecticut Clearinghouse.

Johns Hopkins Medicine.

Lutz, T. Crying: The Natural and Cultural History of Tears, W. W. Norton & Company, 2001.

MassGeneral Hospital for Children.

Mayo Clinic.

National Institute of Diabetes and Digestive and Kidney Diseases.

National Sleep Foundation.

Nemours Foundation.

Nevid, J.S. Health in the New Millennium, Macmillan, 1998.

News release, Texas A&M International University.

Nguyen-Michel, S.T. Appetite, September 2007; vol 49: pp 494-499.

Olive, M.F. Child Abuse and Stress Disorders, Infobase Publishing, 2007.

Owens, J. A Clinical Guide to Pediatric Sleep, Lippincott, Williams & Wilkins, 2010.

Owens, J. Pediatrics, September 1999; vol 104: p e 27.

Penn State Milton S. Hershey Medical Center.

Perez-Chada, D. Sleep, December 2007; vol 30: pp 1698-1703.

Polos, P. Chest, October 2010; vol 138; pp 911A.

Science Daily.

Seaward, B. Managing Stress: Principles and Strategies for Health and Wellbeing, Jones & Bartlett Learning, 2006.

Smith, A. Nutritional Neuroscience, February 2010; vol 13: pp 7-16.

Story, M. Journal of the American Dietetic Association, March 2002; vol 102: pp S40-S51.

The Ohio State University.

Twetman, S. Evidence-Based Dentistry, 2009; vol 10: pp 10-11.

University of California.

University of Maryland.

Valentine, E. The British Journal of Medical Psychology, March 2001; vol 74: pp 115-120.

Vingerhoets, A. Psychological Topics 16, 2007; vol 2: pp 275-296.

WebMD Medical Reference provided in collaboration with The Cleveland Clinic: "Tension-Type Headaches."

Weiss, A. Sleep, September 2010; vol 33: pp 1201-1209.

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