The meaning of health has evolved over time. In keeping with the biomedical perspective, early definitions of health focused on the theme of the body's ability to function; health was seen as a state of normal function that could be disrupted from time to time by disease. An example of such a definition of health is: "a state characterized by anatomic, physiologic, and psychological integrity; ability to perform personally valued family, work, and community roles; ability to deal with physical, biological, psychological, and social stress".[7] Then in 1948, in a radical departure from previous definitions, the World Health Organization (WHO) proposed a definition that aimed higher: linking health to well-being, in terms of "physical, mental, and social well-being, and not merely the absence of disease and infirmity".[8] Although this definition was welcomed by some as being innovative, it was also criticized as being vague, excessively broad and was not construed as measurable. For a long time, it was set aside as an impractical ideal and most discussions of health returned to the practicality of the biomedical model.[9]
The first known appearance of the word "yoga", with the same meaning as the modern term, is in the Katha Upanishad,[10][95] probably composed between the fifth and third century BCE,[96][97] where it is defined as the steady control of the senses, which along with cessation of mental activity, leading to a supreme state.[67][note 13] Katha Upanishad integrates the monism of early Upanishads with concepts of samkhya and yoga. It defines various levels of existence according to their proximity to the innermost being Ātman. Yoga is therefore seen as a process of interiorization or ascent of consciousness.[99][100] It is the earliest literary work that highlights the fundamentals of yoga. White states:
The maintenance and promotion of health is achieved through different combination of physical, mental, and social well-being, together sometimes referred to as the "health triangle."[24][25] The WHO's 1986 Ottawa Charter for Health Promotion further stated that health is not just a state, but also "a resource for everyday life, not the objective of living. Health is a positive concept emphasizing social and personal resources, as well as physical capacities."[26]
Modern yoga is a physical activity consisting largely of asanas, often connected by flowing sequences called vinyasas, sometimes accompanied by the breathing exercises of pranayama, and usually ending with a period of relaxation or meditation. It is often known simply as yoga,[211] despite the existence of multiple older traditions of yoga within Hinduism where asanas played little or no part, some dating back to the Yoga Sutras, and despite the fact that in no tradition was the practice of asanas central.[212]
The Yoga Yajnavalkya is a classical treatise on yoga attributed to the Vedic sage Yajnavalkya. It takes the form of a dialogue between Yajnavalkya and Gargi, a renowned philosopher.[162] The text contains 12 chapters and its origin has been traced to the period between the second century BCE and fourth century CE.[163] Many yoga texts like the Hatha Yoga Pradipika, the Yoga Kundalini and the Yoga Tattva Upanishads have borrowed verses from or make frequent references to the Yoga Yajnavalkya.[164] The Yoga Yajnavalkya discusses eight yoga Asanas – Swastika, Gomukha, Padma, Vira, Simha, Bhadra, Mukta and Mayura,[165] numerous breathing exercises for body cleansing,[166] and meditation.[167]
Tantra is a range of esoteric traditions that began to arise in India no later than the 5th century CE.[180][note 17] George Samuel states, "Tantra" is a contested term, but may be considered as a school whose practices appeared in mostly complete form in Buddhist and Hindu texts by about 10th century CE.[182] Tantric texts include yogic techniques, as well as complex rituals, the use of mantras, devotion towards particular deities and various other practices. Tantric yoga developed complex visualizations which included meditation on the body as a microcosm of the cosmos. They included also the use of mantras, pranayama, and the manipulation of the subtle body, including its nadis and cakras. One of the most popular models of the Hindu tantric body is that of the Kubjikamata tantra (10th century), in which six power centers or cakras of the subtle body as seen as six forms of the goddess Kubjika and her consort. This tantra also contains a teaching on the goddess Kundalini, which resides at the base of the spine and through certain visualization exercises may be made to rise up through the central channel to the crown of the head where she is united with Siva. These teachings on cakras and Kundalini would become central to later forms of Indian Yoga.[183]
Sleep is an essential component to maintaining health. In children, sleep is also vital for growth and development. Ongoing sleep deprivation has been linked to an increased risk for some chronic health problems. In addition, sleep deprivation has been shown to correlate with both increased susceptibility to illness and slower recovery times from illness.[47] In one study, people with chronic insufficient sleep, set as six hours of sleep a night or less, were found to be four times more likely to catch a cold compared to those who reported sleeping for seven hours or more a night.[48] Due to the role of sleep in regulating metabolism, insufficient sleep may also play a role in weight gain or, conversely, in impeding weight loss.[49] Additionally, in 2007, the International Agency for Research on Cancer, which is the cancer research agency for the World Health Organization, declared that "shiftwork that involves circadian disruption is probably carcinogenic to humans," speaking to the dangers of long-term nighttime work due to its intrusion on sleep.[50] In 2015, the National Sleep Foundation released updated recommendations for sleep duration requirements based on age and concluded that "Individuals who habitually sleep outside the normal range may be exhibiting signs or symptoms of serious health problems or, if done volitionally, may be compromising their health and well-being."[51]

According to Tattvarthasutra, 2nd century CE Jain text, yoga is the sum of all the activities of mind, speech and body.[6] Umasvati calls yoga the cause of "asrava" or karmic influx[171] as well as one of the essentials—samyak caritra—in the path to liberation.[171] In his Niyamasara, Acarya Kundakunda, describes yoga bhakti—devotion to the path to liberation—as the highest form of devotion.[172] Acarya Haribhadra and Acarya Hemacandra mention the five major vows of ascetics and 12 minor vows of laity under yoga. This has led certain Indologists like Prof. Robert J. Zydenbos to call Jainism, essentially, a system of yogic thinking that grew into a full-fledged religion.[173] The five yamas or the constraints of the Yoga Sutras of Patanjali bear a resemblance to the five major vows of Jainism, indicating a history of strong cross-fertilization between these traditions.[173][note 16]