Background: In 1965 Altman achieved the hippocampal neurogenesis in rats. In addition, when enough activities are provided in the daytime, and it is suggested that the consolidation of the memory during sleep will be achieved by hippocampal neurogenesis. Aims: We show a recovery method about dementia of neurodegenerative diseases on this article. We introduce our clinical practice of the chronobiological therapy regarding 6 dementia cases. Method: We provided the chronobiological therapy based on awakening-sleep rhythm by daily medical care. We examined autonomic nervous disorders and fluctuating cognition using physical examination. We performed the medication to promote the changes from sleep to awakening-activities in morning. In daytime, our occupational therapy was set, and awakening-activities was made stable. At night we gave the medication to make an active state decreased and stabilize deep sleep. The clinical evaluation was carried out by psychological examination. And Voxel-based Specific Regional Analysis System for Alzheimer’s Disease (VSRAD) of Magnetic Resonance Imaging (MRI), which had been already established, was performed. The conventional study in VSRAD showed the state that the brain atrophy was progressive. Results: About Z-score showing the hippocampal atrophy in VSRAD we accomplished the improvement of 1.28 points from 0.03 about six dementia cases by the chronobiological therapy. These improvements were accompanied by the better changes of the cognitive functions. Conclusion: We speculate that the hippocampal neurogenesis may be derived by reconstructing awakening-sleep rhythm using the chronobiological medicines. If neurogenesis is more dominant than neurodegeneration, dementia associated with the neurodegeneration can be treated.