अथाध्यात्मं प्राणो वाव संवर्गः स यदा स्वपिति प्राणमेव वागप्येति प्राणं चक्षुः प्राणं श्रोत्रं प्राणं मनः प्राणो ह्येवैतान्सर्वान्संवृङ्क्त इति ॥ ४.३.३ ॥
In plain words
Now with respect to the self. The breath is the gatherer. When a man sleeps, speech goes into the breath, the eye into the breath, the ear into the breath, the mind into the breath. For the breath gathers all these to itself.