NDE's

US News article. with lots of examples and discussion.

seeing family members by the elderly and dying is not uncommon.

hallucinations are pathological (psychotic patients hear voices, but seeing visions is usually organic, i.e. drugs or brain damage).

However, normal people have such experience too.

The AmerIndian patients said this was being in contact with "The other side"... and we held ceremonies periodically in our nursing home to keep away the bad spirits that sometimes haunted them.

Some of this might be partly from drugs or isolation: my aunt used to enjoy visions of her family in the nursing home, and even talk to them: when my mom arrived, she would simply come back and be perfectly oriented to reality, so it was not a psychotic experience.

but how about people who are not dying?

Andrew Greeley, in one of his books, commented that he included a "throwaway" question about this in several of his social surveys and said five percent of people have such psychic visions, and most of them tested as mentally normal in the rest of the survey.

however, most folks stay quiet about these things, for fear of being crazy. However, the ones who have psychiatric problems are more open about it, which is why such experiences get a bad reputation.

Catholics consider most of these things as a vivid imagination. But of course God can work via dreams and imagination (and via speaking tongues or inner inspirations, i.e the small quiet voice of conscience and memory). In only a small percentage of cases are such phenomena supernatural: most are a variation of normal ways of perceiving things. (related to art and music creativity).

In some culture, these visions are seen as "real": and here the danger is pride before they decide to get followers to follow them (e.g. cults). The trick for doctors (and clergy) is to discern what is going on: good, harmless, or (in rare case) evil.

but the great majority of such happenings are just part of ordinary life.

yes. And often widows/widowers see or feel the presence of their deceased spouse.

RESULTS:
Overall, evidence suggests a strikingly high prevalence of PBHEs - ranging from 30% to 60% - among widowed subjects, giving consistence and legitimacy to these phenomena.

Via Instapundit, who comments:

This happened with my dad at the end.

My mom would have incidents of what would happen in the future, mainly as dreams.

Me, no. However, as a doc, if I got a bad feeling about someone, I found that I should pay attention to this. Instinct from experience? probably...