There are times when I am in a deep meditation, my body is asleep and relaxed, but my mind is sharp and focused. I can detect the slightest sound and stir in my room. After maintaining this focused mental state in a duration of an hour or so, I would experience a surge of energy pulsing through my body accompany it with a warm sensation. It happens when I am able to hold my body-mind in a still state for at least an hour.
There is not much information about energy surge during meditation. I am speculating that meditation is a very personalized practice, and not everyone experience the same kind of phenomenon due to the uniqueness of our individual life experience. Could it be that the energy body of ours is most likely to surface even in a minuscule second when mind-body is in an intensely aware and profoundly relaxed state? It is a glimpse of our true being, the essence of who we really are.