Here’s a nice article about the significant dreams people have that feature cameo appearances of deceased parents, children, spouses, or friends.
Have you ever experienced such a dream at night, where a dead person appears to help, comfort, or offer assistance? Here’s an excerpt from the piece by Rebecca Cathcart:

“Our dreams have to do with how we internalize the people we love,” said Pamela McCarthy, director of counseling services at Smith College. “You learn to look within for the loved one and the particular function that person played in your life, such as caretaking or guidance in the case of a parent. This becomes part of a function that you can provide for yourself.”
Cultural narratives in regions like Vietnam and North and South America assign special importance to such dreams and consider them actual encounters with the spirits of lost loved ones.
“This notion is so widely shared by traditions all across the globe that some scholars have gone so far as to argue that religion itself actually originated in dream experience,” Kelly Bulkeley, past president of the Association for the Study of Dreams, wrote in his book “Transforming Dreams: Learning Spiritual Lessons From the Dreams You Never Forget.”
You might enjoy reading this Beliefnet.com article by Lisa Schneider about vivid dreams of the dearly departed. Fascinating stuff.