Changing Concepts of Mechanisms of Waking and Sleep States -- Methodology of Morphological and Physiological Substrates Underlying States of Vigilance -- Afferent and Efferent Connections of Brainstem and Forebrain Modulatory Systems -- Neuronal Circuits in the Thalamus, Neocortex, and Hippocampus, Targets of Diffuse Modulatory Systems -- Intrinsic Electrophysiological Properties of Brainstem and Forebrain Neurons -- Neurotransmitter-Modulated Currents of Brainstem Neurons and Some of Their Forebrain Targets -- Synchronized Brain Oscillations Leading to Neuronal Plasticity during Waking and Sleep States -- Brainstem and State dependency of Thalamocortical Systems -- Neuronal Activities in Brainstem and Basal Forebrain Structures Controlling Waking and Sleep States -- Motor Systems -- Neuronal Control of REM Sleep -- REM Sleep as a Biological Rhythm: The Phenomenology and a Structural and Mathematical Model with Application to Depression -- The Role of Active Forebrain and Humoral Systems in Sleep Control.