SB 4.29.71

supti-mūrcchopatāpeṣu
 prāṇāyana-vighātataḥ
nehate ’ham iti jñānaṁ
 mṛtyu-prajvārayor api
Word for word: 
supti — in deep sleep; mūrccha — fainting; upatāpeṣu — or in great shock; prāṇa-ayana — of the movement of the life air; vighātataḥ — from prevention; na — not; īhate — thinks of; aham — I; iti — thus; jñānam — knowledge; mṛtyu — while dying; prajvārayoḥ — or during high fever; api — also.
Translation: 
When the living entity is in deep sleep, when he faints, when there is some great shock on account of severe loss, at the time of death, or when the body temperature is very high, the movement of the life air is arrested. At that time the living entity loses knowledge of identifying the body with the self.
Purport: 

Foolish people deny the existence of the soul, but it is a fact that when we sleep we forget the identity of the material body and when we awake we forget the identity of the subtle body. In other words, while sleeping we forget the activities of the gross body, and when active in the gross body we forget the activities of sleeping. Actually both states — sleeping and waking — are creations of the illusory energy. The living entity actually has no connection with either the activities of sleep or the activities of the so-called wakened state. When a person is in deep sleep or when he has fainted, he forgets his gross body. Similarly, under chloroform or some other anesthetic, the living entity forgets his gross body and does not feel pain or pleasure during a surgical operation. Similarly, when a man is suddenly shocked by some great loss, he forgets his identification with the gross body. At the time of death, when the temperature of the body rises to 107 degrees, the living entity falls into a coma and is unable to identify his gross body. In such cases, the life air that moves within the body is choked up, and the living entity forgets his identification with the gross body. Because of our ignorance of the spiritual body, of which we have no experience, we do not know of the activities of the spiritual body, and in ignorance we jump from one false platform to another. We act sometimes in relation to the gross body and sometimes in relation to the subtle body. If, by Kṛṣṇa’s grace, we act in our spiritual body, we can transcend both the gross and subtle bodies. In other words, we can gradually train ourselves to act in terms of the spiritual body. As stated in the Nārada-pañcarātra, hṛṣīkeṇa hṛṣīkeśa-sevanaṁ bhaktir ucyate: devotional service means engaging the spiritual body and spiritual senses in the service of the Lord. When we are engaged in such activities, the actions and reactions of the gross and subtle bodies cease.