The information coming from the outer and the inner worlds during life is a meaningful influence on the brain phenotypical development and, in our particular topic, on sleep organization. In early developmental stages, from phylogenetic and ontogenetic viewpoints, the sensory information constitutes a relevant drive controlling the brain function and the general physiology. Each brain develops genetically conditioned, although a germane component is the sensory information from both the two worlds and the way the brain handled it throughout life, i.e., an endless process. The natural light-dark sequence, a phylogenically archaic information, through the light receptor and its processing system, profoundly influences the sleep-wakefulness cycle. The circadian rhythm of melatonin secretion -the notion of darkness- is generated in mammals by a central pacemaker located in the suprachiasmatic nuclei of the hypothalamus, largely synchronized by cues from the light-dark cycle. Early in the twentieth century, the concept of the sleep as being the result of a blockade of the auditory inflow was introduced (see 16). Later, Bremer made the proposal of an extensive deafferentation of ascending sensory impulses to the isolated brain that resulted in sleep. He became the outstanding proponent of the deafferentation sleep theory known as the “passive theory”, implicating the existence of a tonus on the central nervous system (CNS) dependent on the sensory information. The activating ascending reticular system described seemed to confirm Bremer’s concepts: every sensory input would also release information (tonus?) to the brain stem activating reticular formation.Sociedad Argentina de Fisiología