Melatonin 3mg and 5mg Compared to Cognitive Behavioral Therapy for Insomnia (CBT-I) in the Treatment of Insomnia

National clinical trials, phase II/III, combined in two stages, randomized, double-blind, controlled, parallel, study of superiority, in which three hundred and seven (307) participants of both sexes, aged equal or more than 55 years will be randomly allocated to one of three treatment groups. In the first stage. The group 01 will use Melatonin 3mg plus CBT-I, the group 02 will use Melatonin 5mg plus CBT-I and the group 03 will use CBT-I plus placebo. Based on the results of an interim analysis will be making a decision on whether to proceed with the study and, if so, on which the doses will be selected for the second stage of the study, to be better studied. The final analysis of the treatments, melatonin in the selected dose plus CBT-I versus CBT-I alone and placebo, will include participants from both stages.