Melatonin for sleep disorders: A bibliometric approach during the last 20years.

Introduction: Melatonin is a neurohormone that it has high interest for sleep researchers. There are some substances uses for sleep disorders. In this sense, melatonin prolonged release has been approved like drug for treatment of primary sleep disorder, and included in a new class of drugs: melatoninergic agonist. We would like to review, first of all the evolution of scientific research about use of melatonin in sleep disorder, and then the evolution of scientist’s paper about melatonin’s formulation, covering the period 1993–2012. Materials and methods: Using Medline database we selected those document that content in their title one or several of the following descriptors: “sleep disorder*” and “melatonin*”. This study took into account all original articles, brief reports, reviews, editorials, letters to the editor, and so on. One of main bibliometric laws were applied: Price’s Law on the increase in scientific literature. This law, undoubtedly the most widely used indicator for the analysis of productivity in a specific discipline or a particular country, takes into account an essential feature of scientific production, which is its exponential growth. Moreover, we conduct a sub-analysis for evolution to different formulation (immediate release and prolonged release melatonin). Results: From the search on Pubmed 36,128 documents (sleep disorder) and 1140 (combined with melatonin) were selected. In order to assess whether the growth of scientific production in sleep disorder and melatonin follows Price’s Law of Exponential Growth, we carried out a linear adjustment of the data obtained, according to the equation y =5.9707x +23.258, and another adjustment to an exponential curve, according to the equation y =27,915e0.0927x. Mathematical adjustment to an exponential curve, allows us to obtain a correlation coefficient r =0.828. On the other hand, linear adjustment to the measured values provides an r =0.924. The repertoire analyzed is more suited to a linear adjustment than an exponential adjustment. Moreover, 2% of total documents corresponding to prolonged release melatonin. And of these, 80% have been published in the last 5years. Conclusion: To conclude a high papers on sleep disorder has been published, but for melatonin not fulfillment of Price Law. However, prolonged-release melatonin has increase in the last few years. [Copyright &y& Elsevier]