This question came up for me today and had me searching for more information. A doctor diagnosed a student at one of my schools with AD/HD but also noted the possibility of sleep disorder. The symptoms of sleep deprivation can be almost indistinguishable from those of AD/HD. Many individuals with a sleep disorder have difficulty focusing, exhibit impulsivity, have trouble completing tasks, and experience memory lapses. If these behaviors sound familiar, you probably know someone with AD/HD. This article from The Huffington Post cites the many similarities between the conditions, the results of studies with children who are sleep-disordered, and why it is so easy to misdiagnosis a sleep disorder. To learn more, visit http://www.huffingtonpost.com/dr-michael-j-breus/adhd-sleep-disorders_b_3193570.html