The experimental induction of neurosis in monkeys through changes in their diurnal rhythm is described. Monkeys' higher nervous activity is complex and resilient to trauma, making it difficult to induce neurosis using traditional methods. Neurosis was only observed in monkeys with weak nervous systems and inert processes, responding to complex tasks. D. I. Miminoshvili's method using conflict and natural stimuli was more successful. In this study, neurosis was induced by altering the diurnal rhythm, creating a distorted or biphasic rhythm. This disruption could cause cerebral cortex dysfunction. Three monkeys of the species Papio hamadryas were tested. Motor alimentary conditioned reflexes were established using light, bell, and tone. All monkeys were of the strong type, but Bronenosets was weaker. Nosorog showed excitation, while Dog and Bronenosets had inert processes. The monkeys were placed in an artificial diurnal regime opposite to their natural one, leading to a distorted rhythm. After adaptation, the regime was changed to biphasic days, then reversed. Continuous illumination was replaced by darkness. After two months, all monkeys developed neurosis, with severe derangement of conditioned reflexes. Nosorog was highly excited, pressing levers repeatedly. Dog was inactive, only pressing the lever at the end. Bronenosets showed a paradoxical phase, with stronger lever pressure after light than after the bell. Neurosis persisted for a few months after returning to normal conditions. Initial kymograms of conditioned reflex activity were similar in all monkeys. Nosorog showed no cardiac disturbances. Two months later, she became sluggish and trembled, then began to eat and lay motionless.The experimental induction of neurosis in monkeys through changes in their diurnal rhythm is described. Monkeys' higher nervous activity is complex and resilient to trauma, making it difficult to induce neurosis using traditional methods. Neurosis was only observed in monkeys with weak nervous systems and inert processes, responding to complex tasks. D. I. Miminoshvili's method using conflict and natural stimuli was more successful. In this study, neurosis was induced by altering the diurnal rhythm, creating a distorted or biphasic rhythm. This disruption could cause cerebral cortex dysfunction. Three monkeys of the species Papio hamadryas were tested. Motor alimentary conditioned reflexes were established using light, bell, and tone. All monkeys were of the strong type, but Bronenosets was weaker. Nosorog showed excitation, while Dog and Bronenosets had inert processes. The monkeys were placed in an artificial diurnal regime opposite to their natural one, leading to a distorted rhythm. After adaptation, the regime was changed to biphasic days, then reversed. Continuous illumination was replaced by darkness. After two months, all monkeys developed neurosis, with severe derangement of conditioned reflexes. Nosorog was highly excited, pressing levers repeatedly. Dog was inactive, only pressing the lever at the end. Bronenosets showed a paradoxical phase, with stronger lever pressure after light than after the bell. Neurosis persisted for a few months after returning to normal conditions. Initial kymograms of conditioned reflex activity were similar in all monkeys. Nosorog showed no cardiac disturbances. Two months later, she became sluggish and trembled, then began to eat and lay motionless.