1. Abdulaziz M.; Tran, Trinh T.; Alkadhi, Karim A.. European Journal of Neuroscience, Apr2010, Vol. 31 Issue 8, p1368-1376, 9p, 6 Graphs; DOI: 10.1111/j.1460-9568.2010.07175.x This article does conclude that there are direct long term effects of caffeine on sleep habits. I think long term effects of caffeine on sleep disorders after caffeine consumption is reduced is a important aspect of the disorder to discuss.
2. (Adapted from Griffiths, R.R., Juliano, L.M., & Chausmer, A.L. (2003). Caffeine pharmacology and clinical effects. In: Graham A.W., Schultz T.K., Mayo-Smith M.F., Ries R.K. & Wilford, B.B. (eds.) Principles of Addiction Medicine, Third Edition (pp. 193-224). Chevy Chase, MD: American Society of Addiction) I think this article is a credible source. The authors of this article are from John Hopkins School of Medicine. The article describes the average caffeine consumption of individuals, and discusses the numerous effects of consuming too much caffeine.
3. ^ a b Peters, Josef M. (1967). "Factors Affecting Caffeine Toxicity: A Review of the Literature". The Journal of Clinical Pharmacology and the Journal of New Drugs (7): 131-141 url = http://jcp.sagepub.com/cgi/reprint/7/3/131. I like this article; it seems to be a very in depth source that covers all aspects of caffeine consumption.
4. Journal of Neuroscience,11 May 2011, 31(19):6956-5962
Caffeine is the most often used stimulant in the world. The average daily consumption of caffeine for adults in the united states is approximately 280 milligrams.</ref> Journal of Neuroscience,11 May 2011, 31(19): 6956-6962<ref>