Background: Upanishads describe the three avastha (states) of mind/consciousness as Jagrita, Swapna and Sushupti. Though the epistemology of the names of these states of mind is indicative of a wakeful to deep sleep states of mind, explanations in Upanishads make it clear that these are the states of spiritual consciousness. Stages of sleep have been studied elaborately over time. Polysomnographic and biological findings have helped to identify distinct stages of sleep. Materials and Methods: This study is a sincere effort to comparatively find out any similarities or dissimilarities in the concept of these states of mind and stages of sleep in Upanishads and contemporary medical science literature respectively. Results and Discussion: The mind differently functions and actualizes itself from gross to subtle things in the different avastha of mind. Interesting observations were found like states of mind were close to the measure of mindfulness index of mind. In the case of stages of sleep, different brain waves, activities of mind like cognition, memory and restoration of normalcy of brain tissues have been found to be happening to varying degrees in different stages. Conclusion: Proper recommendations were made for the further studies to understand and validate the concept of states of mind and for the application of these concepts in the fields of sleep medicine and psychotherapy.