How a devotee can be in a state of insanity because of ecstatic love is described in the Tenth Canto, 30th Chapter, 4th verse of Śrīmad-Bhāgavatam, where the gopīs were searching for Kṛṣṇa in the forests of Vṛndāvana. The gopīs were loudly singing the glories of Kṛṣṇa and wandering from one forest to another in search of Him. They knew that Kṛṣṇa is not localized, but all-pervading. He is in the sky, He is in the water, He is in the air, He is the supersoul in everyone's heart. Thus the gopīs began to inquire from all kinds of trees and plants about the Supreme Personality of Godhead. This is an instance of ecstatic madness on the part of devotees.
Similarly, there are symptoms of diseases caused by ecstatic love. This condition is credited by learned scholars as mahābhāva. This highly elevated condition is also called divyonmāda, or transcendental madness.
Forgetfulness
When Kṛṣṇa was absent from Vṛndāvana and was staying in Mathurā, Śrīmatī Rādhārāṇī sent news to Him that His mother, the Queen of Braja, was feeling such separation from Him that there was foam coming from her mouth, like the foam on the shore of the ocean. And sometimes she was raising her arms like the waves of the ocean, and because of her intense feelings of separation, she was rolling on the ground and creating a tumultuous roaring sound. And sometimes she was remaining completely silent, like a calm sea. These symptoms of separation from Kṛṣṇa are called apasmāra, or forgetfulness. One completely forgets his position when he manifests these symptoms in ecstatic love.