Nidra and Manas Bhava: A Correlative Review of Rajas and Tamas Guna With Modern Sleep Physiology

Background: Nidra (sleep) is an essential physiological process that contributes to physical restoration, cognitive functioning, emotional regulation, and overall well-being. Ayurveda recognises Nidra as one of the three Upastambha, along with Ahara and Brahmacharya. The Ayurvedic understanding of sleep incorporates the functioning of Manas and the influence of the three Gunas—Sattva, Rajas, and Tamas. Aim: To critically review the relationship between Nidra and Manas Bhava, with particular emphasis on Rajas and Tamas Guna, and to explore their conceptual correlation with contemporary sleep physiology. Materials and Methods: A narrative review was undertaken using classical Ayurvedic literature, including Charaka Samhita and Sushruta Samhita, along with published scientific literature concerning sleep regulation, psychological stress, cognitive arousal, and emotional functioning. Relevant concepts were examined to identify areas of conceptual convergence and differences between traditional Ayurvedic explanations and modern physiological knowledge. Review: Ayurvedic literature describes sleep in relation to the functional state of Manas, Indriyas, and the predominance of Tamas. Rajas, associated with activity, stimulation, and mental agitation, provides a conceptual framework for discussing persistent mental activity that may interfere with sleep. Modern research identifies psychological stress, repetitive negative thinking, and cognitive hyperarousal as factors associated with sleep disturbances. Sleep itself also influences memory, attention, mood, and emotional regulation. These findings support an interdisciplinary examination of the relationship between mental states and sleep, although the Ayurvedic Gunas cannot be considered direct equivalents of modern neurophysiological mechanisms. Conclusion: Nidra and Manas Bhava represent interconnected dimensions of health in Ayurveda. The concepts of Rajas and Tamas offer a traditional framework for examining mental activity and sleep, while contemporary sleep science provides complementary explanations of sleep–wake regulation. Further empirical research using validated psychological and sleep-assessment tools is required to establish measurable associations between Ayurvedic constructs and modern clinical parameters.