Nearly every night, Martin Hornung's nightmare unfolds to the same haunting strains. Of Auschwitz. Of screaming voices. Of scenes he would rather not relive in the light of day. "I'm almost afraid to go to sleep," the 86-year-old retired computer engineer said. The horrors that revisit Hornung in the dark are common among Holocaust survivors, and are a reason why he refuses to enter a nursing home despite his myriad health problems. Jewish organizations worldwide are working to keep survivors out of such facilities, where the surroundings and routines - strangers in uniforms, desolate shower rooms, medical procedures - can exacerbate flashbacks. "It frightens them and brings them back to the Holocaust," said Dr. Jaclynn Faffer, executive director of Ruth Rales Jewish Family Service, one of the groups helping keep survivors out of nursing homes. Hornung wouldn't even consider moving into a nursing home. "I would kill myself." An estimated 93,000 Holocaust survivors are alive in the United States, and South Florida is home to one of the largest populations. The youngest are in their mid-60s, but many are much older. There is no definitive breakdown of how many are living independently and how many receive assistance, but many are living below the poverty line and in need of help. "Their capacity for resilience that they've shown since the war is amazing," said Paula David, a social worker who has worked with more than 2,000 Holocaust survivors in Toronto over the last 20 years and has studied the specific problems of the population as it ages. "The hard part is no matter what we do, we can't make it OK." Flashbacks can come to a survivor at any time. A fire alarm. A foreign accent. Standing in a line. Once, David witnessed a survivor begin screaming on a High Holy Day as musicians performed. The music happened to have been played as murders took place at the concentration camps. One of David's clients slept with hiking boots under his pillow to ensure he'd be able to run away. Another one hoarded bread in his closet so he wouldn't starve. For Alex Moscovic, who survived Birkenau and the horrific medical experiments of Josef Mengele, a flashback came in the dermatologist's chair. Moscovic needed to have a dime-sized cancerous growth removed. The doctor cauterized the area _ and the patient began to shake uncontrollably. "The smell - it brought me back," the 77-year-old Moscovic said. "The only way you really left Birkenau was through the smokestacks." Experts have seen similar reactions from other populations, including war veterans and survivors of genocide in Rwanda and elsewhere. The flashbacks are only expected to get worse as these groups age, so caregivers are trying to impart lessons learned from the Holocaust survivors. For these Jewish survivors, being allowed to stay in their homes offers a measure of comfort and routine as so much else around them changes. The Ruth Rales group provides Hornung a nurse's aide three days a week, and he also receives delivered meals. Hornung cared for his wife - also a survivor - for 10 years as she slipped into a haze of Alzheimer's, which along with other forms of dementia further complicates the aging process of survivors. She grew so confused she would think her husband was a Nazi guard. Once, she stabbed him in the chest. After his wife died in 2001, Hornung was diagnosed with colon cancer. He's still lucid, but he struggles with respiratory problems. On a recent afternoon, he couldn't get through a complete thought without slipping into a hacking cough. Ann Speier, 85, has long been retired from her dressmaking job, and like Hornung, lives in Century Village in Boca Raton. It's a popular place for survivors in their final years. She, too, is haunted by memories. "I try not to think, but I have to," she said. "It doesn't go away." Three days a week, her aide arrives to take her to the doctor, to help her to the pool and to assist around the house. Without the help, she said, she couldn't exist. Speier's vision is nearly gone. Everything and everyone is just a blur. But she recognizes Lila Vaughn, her caseworker from Ruth Rales, when she arrives. She beams. She caresses Vaughn's face. And after some time passes, the caseworker has a question for Speier. "Do you want me to leave or you want me to stay?" Vaughn asks. "I would like you to stay all day with me," Speier answers. "It's so hard. It's so lonely."