" And it came to pass that he returned to his own house at Jerusalem; and he cast himself upon his bed, being overcome with the Spirit and the things which he had seen."
After learning the things of the Lord Lehi when back to his own home, pondering the things he had witnessed. This can be found often as well, that hose whom have learned the things of the Lord go home or are commanded to return to their own houses to ponder the things they have learned. Every Sunday members of the church now are encouraged to go home after our meetings and discuss what was learned in the time we teach the gospel. Home should be a place of learning and of the Spirit.
The power of God and of the Spirit is so strong that the human body cannot handle the strain. Leading into exhaustion as in the case of Lehi or other effects, such as hunger, or rarely illness. The body may feel weakness when filled with the Spirit, but the weakness can then be turned to strength in the Lord.