Only if a person wills it. Such people are known as mediums, who, through concentrated effort, allow their minds to be inhabited by disincarnate entities, an act which eventually dislocates their mental body, helping them develop tremendous psychological imbalance.
However, there is no danger for individuals during astral projection for entities to enter their bodies when they are not practicing mediumship. One will also not experience problems with negative visitors by performing a circle of protection, a seal of Christic force, around their bedroom or home at night after conjuring. One can use the Conjurations of the Four and the Seven, finishing with the Invocation of Solomon, to protect oneself, invoke the superior intelligence of Christ in preparation for dream yoga, and keep away all intruders.
Joyful in hope, suffering in tribulation, be thou constant in thy prayer.
Benedictis, qui venit in nomine Domini. Osanna in excelsis.
"Blessed is he who comes in the name of the Lord. Hosanna in the highest!"