Many centuries before the advent of the Aryans into India, the Indus Valley civilization flourished in this region as is evident from the excavations at Mohenjo-Daro and Harappa. Most of these regions are now in Pakistan. The knowledge of the original inhabitants about body function and medicine must have been based on magical, religious, and empirical practices [1]. When the Aryans entered the Indus Valley, they brought with them their knowledge of gods, medicine, and physiology. The chief sources of their culture and knowledge were the four Vedas . Four Vedas (books of knowledge), twelve Upanishadas (brief catechistical treatises) and various Smritis (canons of law) are the principal sources of knowledge of ancient Indian Philosophy . Though these scriptures are believed to have been brought to India by the Aryans, there is definitive evidence to assume that many elements of the Indus Valley civilization were assimilated by the Aryans [1].

According to traditional Indian belief (or Hindu religious belief) the Vedas were told to the sages by Brahma, the creator of man, probably about 6000 years before Christ. But according to most scholars, even the Rig Veda, which is the oldest among Vedas, is not older than 2000 years before Christ [1]. The four Vedas are Rig Veda, Sama Veda, Yajur Veda, and Atharva Veda. They contain hymns and prayers addressed to different deities. Even in these purely religious texts we find a reflection of anatomical, physiological, psychological, pathological, and therapeutic views, which may have some symbolic origin and which had found their reflection in the traditional Indian medicine, called Ayurveda . The meaning of the term Ayurveda is knowledge of life [2, 3, 4]. Though the word Ayurveda sounds as if it is related to the Vedic period, it was derived much later. According to traditional Indian belief, Brahma, the creator, also provided the knowledge contained in the Ayurveda. Unfortunately, Ayurveda in its original form is not available now, but most of its contents are revealed in the Samhitas (encyclopedia) written by Charaka and Sushruta in 1000 BC [5, 6].

Charaka has dealt with sleep and sleep disorders in more detail. Charaka Samhita gives details about his approach to sleep. According to Ayurveda, there are three Dhatus (basic factors) which decide the health or ill health of an individual. They are called Vata, Kapha, and Pitta. They cannot be translated into any other language, as they do not have any equivalent terminology either in modern physics or in physiology and medicine. When they are in their natural state they provide the individual with strength, happiness, and long life. On the other hand, if these Dhatus are altered they bring about health problems. According to Ayurvedic concepts nidradhikya (excessive sleep) is caused by disturbance in Kapha, and asvapna (sleeplessness) is caused by disturbance in Vata.

According to Charaka Samhita “When the mind gets tired, when the senses get dulled and incapable, the man goes to sleep.” In Ayurveda sleep is classified into seven types on the basis of its causative factors. Sleep can be either physiological or pathological [2, 1]. Thus seven types of sleep are produced as a result (or consequence) of night time (physiological sleep), tamas (ignorance), kapha (one of the basic factors or Dhatus), mental exertion, physical exertion, bad prognosis of disease or as a side effect of disease (e.g. fever). The night sleep is considered good, and it is described as that which “nurses all the living beings.” The sleep which is caused by tamas is considered as “the root cause of sinful acts.”

Proper or improper sleep would decide whether you are happy, miserable, obese, emaciated, strong, weak, virile, sterile, knowledgeable or ignorant, long-lived, or short-lived. The Charaka Samhita goes on to say that if the sleep is proper it brings about happiness and longevity . The consequences of both deficient and excess sleep will be just the opposite. Sleeping during the day time, in all seasons, is advocated for the young, weak, tired, and those suffering from various diseases. During summer season (when nights become shorter) some sleep during the day is advocated for all. In other seasons, daytime sleep is not advocated. Although any comfortable position of the body may be regarded as suitable for sleep, sleeping on one’s right side (daksirasana) is considered the most favorable position for sleep. According to them sleeping in sitting posture does not produce any harm. Keeping awake during night causes roughness in the body. Obesity and emaciation are specially mentioned as two conditions caused by improper sleep and diet.

For some reason, if one does not get sleep, it can be achieved by massage, bath or by consuming milk, rice with curd, alcohol, meat soup or by listening to some agreeable music [2, 4]. In addition, the following medicinal preparations are suggested for curing insomnia [2]: