¹Division of Sleep Medicine at Harvard Medical School and WGBH Educational Foundation. (n.d.). Why do we sleep, anyway? Healthy Sleep . Retrieved from http://healthysleep.med.harvard.edu/healthy/matters/benefits-of-sleep/why-do-we-sleep^[1].

²National Sleep Foundation. (n.d.). What happens when you sleep? Retrieved from http://www.sleepfoundation.org/article/how-sleep-works/what-happens-when-you-sleep^[2].

³Division of Sleep Medicine at Harvard Medical School and WGBH Educational Foundation. (n.d.). Consequences of insufficient sleep. Healthy Sleep. Retrieved from http://healthysleep.med.harvard.edu/healthy/matters/consequences^[3].

⁴Spira, A. P., Gamaldo, A. A., An, Y., Wu, M. N., Simonsick, E. M., Bilgel, M., … & Resnick, S. M. (2013, October). Self-reported sleep and β-amyloid deposition in community-dwelling older adults. The Journal of the American Medical Association Neurology. doi:10.1001/jamaneurol.2013.4258.

⁵American Psychological Association. (2004, May). More sleep would make most Americans happier, healthier and safer. Retrieved from http://www.apa.org/research/action/sleep-deprivation.aspx^[4].

⁶National Sleep Foundation. (n.d.). How much sleep do we really need? Retrieved from http://www.sleepfoundation.org/article/how-sleep-works/how-much-sleep-do-we-really-need^[5].

⁷Ibid.

⁸The four generations are defined as the following: Millennials (18- to 34-year-olds), Gen Xers (35- to 48-year-olds), Boomers (49- to 67-year-olds) and Matures (68 years and older).