Аннотация:Sleep is quantitatively described by subdividing polysomnographic records into intervals each ofwhich is allocated to one of the just 5 all-or-nothing variables called “sleep–wake stages”. What are themechanisms governing the establishment of such 5 relatively stable stages and rapid transitions betweenthem? We modeled these stages as resulting from the competing interactions between the mutually inhibiting drives for wake, NREM sleep, and REM sleep that are proposed to work in a similar way as two-, two-,and one-way switch, respectively. The electromechanical counterparts of the stages were visualized as 5variants of an electrical circuit connecting these switches with three lamps. During W and transient stateN1, two sleep switches are switched off, and three lamps are turned off. During other transitions, one ofthese lamps is turning on after changing in on–off state of one or two of three switches. During transitionsto N2, one (N2) lamp is turning on. During the following transitions to N3, one more (N3) lamp is turningon. During transitions from N2 to R, the N2 lamp is turning off, while the R lamp is turning on. Estimatesof stage-specific scores on the 1st and 2nd principal components of the electroencephalographic spectraprovided empirical evidence for such on–off states of these switches.