Is it true that those who study Torah begin to feel spiritual sensations?

I have a friend who went to a yeshiva and told me that after about six months of very intensive study, he began to feel drug-like sensations throughout his body. At first, only during various parts of the prayers, and then also without any connection to the prayers. I also understood from things he said that there were other things he felt and all sorts of "spiritual experiences". How does the rabbi explain this? He doesn't seem like he's mentally ill or anything. On the contrary, he's a very rational guy, connected to the ground, to the world, to reality.

See the book “Midrachi Aliya” by Rabbi Yaakov Ades.
Of course, one can argue that the mind is flexible and the experience is in the head, but the dream is real, even if subjective.

This is what is called guided imagery. The person convinces himself that there is something special in the religious ritual and then experiences it.
There are thousands of similar cases documented among Christians, such as Joseph of Cupertino, for whom there is evidence that he levitated. In the East there are also many similar cases, and among Muslims there are factions that claim similar experiences.

In my experience, most people do not usually experience such experiences. But sometimes religious rituals can evoke such an emotion.

There are also studies that have shown a connection between temporal lobe epilepsy and religious experiences. There are also studies that claim that the religious experience originates from guided imagery and self-hypnosis.

There is a very strong force in our souls called the ‘power of imagination’. And most of the sensations that people experience are imagination.
It is advisable to carefully read Maimonides”s introduction to Tractate Avot. As well as in the Teaching of the Perplexed, in several places our rabbis expand on this power.