Conceptual Study of Nidra from Various Samhitas

Nidra (sleep) is regarded as one of the Trayopasthambha (three supporting pillars of life) in Ayurveda, along with Ahara (diet) and Brahmacharya (regulated lifestyle). A conceptual study of Nidra from various Ayurvedic Samhitas such as Charaka Samhita, Sushruta Samhita, Ashtanga Hridaya, and later texts highlights its physiological, psychological, and pathological significance. The classics describe Nidra as a natural, essential function of the body that ensures nourishment, mental clarity, and balance of Doshas. Charaka emphasizes the role of Nidra in health, immunity, complexion, strength, and longevity, while also categorizing abnormal sleep into Asatmya Nidra (improper sleep) and Vikara Nidra (disease-related sleep). Sushruta associates Nidra with the withdrawal of senses and mind, considering it as a restorative phase for the body. Vagbhata further classifies Nidra according to causation—natural, doshic, psychological, and pathological origins. Disturbances in Nidra, whether insufficient (Anidra) or excessive (Atinidra), are seen as causative factors for a wide range of diseases including metabolic, neurological, and psychiatric disorders. Thus, the conceptual review of Nidra across Samhitas demonstrates its multidimensional role in health and disease, and its regulation is central to holistic well-being in Ayurvedic science.