In her notes, Mrs. Brennan described the episode as a “hallucination,” a red flag for delirium. When the episode was recounted to Dr. Kerr and Anne Banas, a Hospice Buffalo neurologist and palliative care physician, they preferred the term “vision.”

“Is there meaning to the vision or is it disorganized?” Dr. Banas asked. “If there is meaning, does that need to be explored? Does it bring comfort or is it distressing? We have a responsibility to ask that next question. It can be cathartic, and patients often need to share. And if we don’t ask, look what we may miss.”

Dr. William Breitbart, chairman of the psychiatry department at Memorial Sloan Kettering Cancer Center, who has written about delirium and palliative care, said that a team’s response must also consider bedside caregivers: “These dreams or visions can be interpreted by family members as comforting, linking them to the legacy of their ancestry.

“But if people don’t believe that, they can be distressed. ‘My mother is hallucinating and seeing dead people. Do something about it!’” Dr. Breitbart trains staff to respect the families’ beliefs and help them understand the complexities of delirium.

Some dream episodes occur during what is known as “mixed-state sleep” — when the boundaries between wakefulness and sleep become fragmented, said Dr. Carlos H. Schenck, a psychiatrist and sleep expert at the University of Minnesota Medical School. Jessica Stone, the teenager with Ewing’s sarcoma, spoke movingly about a dream of her dead dog, Shadow. When she awoke, she said, she saw his long, dark shape alongside her bed.

Dr. Banas, the neurologist, favors the phrase end-of-life experiences. “I try to normalize it for the family, because how they perceive it can push them away from that bedside or bring them closer,” she said.

Reliving Trauma

The patient had never really talked about the war. But in his final dreams, the stories emerged. In the first, the bloody dying were everywhere. On Omaha Beach, at Normandy. In the waves. He was a 17-year-old gunner on a rescue boat, trying frantically to bring them back to the U.S.S. Texas. “There is nothing but death and dead soldiers all around me,” he said. In another, a dead soldier told him, “They are going to come get you next week.” Finally, he dreamed of getting his discharge papers, which he described as “comforting.” He died in his sleep two days later. — John, 88, who had lymphoma.

