Srila Prabhupada said:

Last night we were discussing Raghunatha dasa Gosvami. In his later life, he almost completely abstained from eating and sleeping. He would drink only a little buttermilk every three or four days, and he worked twenty — two hours a day, sleeping two or three. And some days he did not sleep at all. So you may ask, "How could he survive?" Actually, he lived for one hundred
years. Eating, sleeping, mating and defending were not problems for Raghunatha dasa Gosvami, but still he lived. Because he was a pure devotee of Krsna, he was fully aware that the soul is eternal and independent, although it has been put into this bodily cage, which it actually does not require.

From LCFL ch. 7