Devadatta is the name of one of the ten vital air streams (vayu) flowing along the nadis (channels) in the human body. Devadatta Vayu is responsible for the sleep state and yawning. This is mentioned in Yogachudamanya Upanishad (Verse 25).
The names of the ten vayus, their locations, and functions are found mentioned in Trisikhi Brahmana Upanishad (verse 77), and Yoga Yajnavalkya (IV 48-72).
The concept of vayu is based on the presupposition that the life-activity of living organisms cannot belong to or manifest itself in any material object, and that it can only issue from a special spiritual, non-material entity. Spiritual reality was given names like atman, Brahman, jiva, bhakta, purusha, atma and so on by the ancient Indian thinkers.
Life itself is supposed to be derived from this spiritual reality. However, the energy required for various activities going on in the body, such as digestion, excretion, sensations, physical movements, respiration, etc., was supposed to come from the vital air-flows or vayus. Only so long as the vayus were flowing along the nadis, life activity could continue.