Introduction The objective of this study is to analyze the improvements in sleep and quality of life, as well as to evaluate the decrease or cessation of drug treatment in a sample of insomniacs in hypnotic drug treatment after CBT-I application. Materials and methods This is a pre-post quasi-experimental design, with a monitoring performed 6 months later in which information of an Experimental Group (EG = 17) is given and evaluated during three times, and also a Control Group (CG = 44), with measures only at the pre- post. According to Perlis Protocol and after an Insomnia Interview by Morin, all patients qualified as candidates for CBTI. Patients were given a daily sleep log and the Spanish version of the following assessment tools: Insomnia Severity Test (IST), Pittsburg Sleep Quality Index (PSQI), Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI) and Health Survey (SF-36). The following variables were noticed through these tests: Sleep Onset Latency (SOL); Total Sleep Time (TST); Total Time in Bed (TTB);Sleep Efficiency index (SE%); aWakenings (W), Total Wake Time (TWT); time aWake After Sleep Onset (WASO), Sleep Quality (SQ). Results The CBT-I produced the following positive effects: (i) significant pre-post effects that were maintained at 6 months: STI ( p p p p p p p p p p p p p p p p p p p p p p p Conclusion CBT-I, has been useful for the improvement of sleep quality, diminishing the severity of insomnia and improving other aspects of physical health (physical function and general health), as well as other aspects of mental health, particularly reducing anxiety. The diminution of TBT and TWT, along with the increase of TST, caused an increase in the SE. These seem to be the most evident influences of CBT-I in sleep parameters. Acknowledgements W. Gralke for his help in the transfering data; Dr. J. Marquez and Dra. A. Perez, Health Service of the city of Valencia; University of Valencia: Practicums; J.R. Diaz and A. Batalla, Sleep Unit of Castellon Hospital; M. A. Maroto, for his teachings.