White male rats, intact and pregnant females were subjected for 3 days to deprivation of paradoxical sleep by the technique of Jouvet. The main resulting vectors of the extreme state outcome, i.e., lethality, susceptibility to stress, and neurotization, made it possible to establish corresponding levels of resistance. A relationship of each of the levels with the ability to form conditioned reflexes, initial functional interhemispheric asymmetry and behavioural status, expression of protective reactions and paradoxical sleep under conditions of an insoluble conflict situation was followed. High resistance of pregnant rats is considered to be associated with the formation of gestational ambilaterality of the brain of intact animals. Such an increase in resistance is selective as far as it concerns the organism of the pregnant and it does not ensure stability of the feto-maternal complex under extreme conditions. It was established that there was an inverse relationship between the expression of neurotic disorders of the higher nervous activity and vegeto-morphological features of acute stress. This gives reason to define more exactly the role of neurotic disorders in the pathogenesis of stress and mechanisms of resistance to extreme factors.