When he is dominated by the light, then this deity does not see dreams; then, in this body, that bliss arises.

Tejasā abhibhūtaḥ — “dominated by light.” This refers to the state of suṣupti (deep dreamless sleep) or even deeper, to the state of turīya (the fourth state, beyond waking, dreaming with dreams, and dreamless sleep).

When the light of the Self (ātman, brahman) becomes predominant, the mind projects no more dreams (svapnān na paśyati). Dreams are projections of vāsanās (residual tendencies); when these dissolve in the light of consciousness, there is no more dream content.

Tat sukham bhavati — “that bliss arises.” This is the ānanda mentioned in the Taittirīya Upaniṣad as the sheath of the Self. It is bliss without cause, not dependent on objects, the blessedness of pure existence.

For the yogī: the objective of meditation is to reach this state of light (jyotis) where there are no more mental projections, only the peace and bliss of the Self.