The nurse was frantic. She’d just seen two elderly people having sex in a room at the Hebrew Home at Riverdale, N.Y. She asked Daniel A. Reingold, then the home’s executive vice president, what she should do.

“Tiptoe out and close the door so you don’t disturb them,” he told her.

Today, Reingold likes to recount the 19-year-old tale to show why the Hebrew Home broke with industry practice and encouraged sex and intimacy among its elderly residents, including those with Alzheimer’s and other forms of dementia.

In 1995, the home adopted a four-page policy — considered the first of its kind — stating that residents “have the right to seek out and engage in sexual expression,” including “words, gestures, movements or activities which appear motivated by the desire for sexual gratification.”

Beverly Herzog, an 85-year-old widow who recently moved to the Hebrew Home, said, “Intimacy is the most natural, normal thing in the whole world. It keeps you young, it gives you something to look forward to. It’s not easy to get into a cold bed.”

Said Reingold, now president and chief executive officer of the home: “We honor what remains in a person, not what’s gone.”

No one keeps track of how many of the nation’s 16,000 elderly care facilities have policies like the Hebrew Home’s. Greg Crist, a spokesman for the American Health Care Association, an industry trade group, said, “I’m not aware of anything that’s consistent.”

Instead of specific sexual-expression policies, some of the nation’s larger operators of nursing homes — including Genesis HealthCare Corp. of Kennett Square, Pa., and Golden Living of Plano, Texas — said they address the issue on a person-by-person basis, with training about sexual situations built into broader programs.

“This is an industry that is changing daily,” said Charlotte Patterson, a registered nurse who is vice president and associate general counsel of health care at Golden Living, which operates more than 300 nursing homes in 21 states. “We don’t have hard and fast rules because that could lock you into something you don’t want to be locked into. It’s important that we constantly keep that discussion going with our residents, our facilities and our staff.”

The $120.6 billion nursing home industry is expected to grow by an annual average of 3.6 percent to about $144 billion by 2018, according to industry research firm IBISWorld. The growth might be stronger if not for reductions in Medicare and Medicaid reimbursements and increased use of in-home services.

Hebrew Home’s sexual-expression policy is unusual, partly because many facilities lack the time, resources or inclination to confront the subject.

“There are still a lot of nursing homes that have their heads in the sand,” Reingold said.

That could change with the aging of the Baby Boom generation. By 2030, people 65 and over are expected to number more than 72 million, up from 40 million today, according to the Census Bureau. Baby Boomers, who started moving into that group in 2011, are sexually freer, living longer and using drugs such as Viagra.

Barring medical breakthroughs, the Alzheimer’s Association expects the number of those 65 and over with Alzheimer’s to grow to 7.1 million by 2025. Elderly-care residents with dementia can raise difficult legal, ethical and moral issues for caregivers who must determine whether those residents have the mental capacity to consent to sex.

In “To Be or to Exist,” a 2009 article in the Indiana Law Review, Evelyn Tenenbaum, a professor at Albany Law School in Albany, New York, wrote that, although desire for intimacy persists in people with dementia, “nursing homes cannot freely allow sexual relationships” between them. Homes “must intervene to ensure that unsafe and abusive relationships do not occur,” she wrote.

The Hebrew Home was founded in 1917. Today, the 870-bed facility sits on a 32-acre sprawl of brick pavilions atop a grassy slope along the Hudson River. The resident population counts 23 centenarians and has a median age of 86.

With an annual budget of almost $105 million, a staff of more than 1,000 and donors including famed lawyer David Boies and former American International Group chief Maurice Greenberg, the nursing home has greater resources than many in its field. (Bloomberg L.P., the parent company of Bloomberg News, also has donated to the Hebrew Home over the years.)

Reingold, 58, started working at the home in 1990, when his father was CEO. He soon became aware that residents regularly had sex. In 1994, staffers filled out a questionnaire about their attitudes toward it. Some wanted the sex stopped altogether, some thought it was funny, some considered it disgusting.

“It reflected their personal backgrounds,” Reingold said.

A group of 11 staffers spent eight months writing a policy designed to reduce personal, religious, ethnic or other bias workers might bring to their interpretation of a sexual encounter.

“Generally,” the policy said, “it is the function and responsibility of staff to uphold and facilitate resident sexual expression.”

The policy gave residents rights to books, magazines, films and other materials with explicit sexual content, as well as to private space. Lack of privacy has often been cited in nursing home surveys as a primary obstacle to intimate relationships. Reingold recalled joking with a woman that maybe the Hebrew Home should offer an “intimacy room” for rental by the hour.

“She said, ‘Mr. Reingold, at our age, we’ll need it for more than an hour,’” he said.

The policy also was intended to comply with federal law giving residents essentially the same rights they’d enjoy outside the facility. Sex is as much a civil right as the right to vote, Reingold said.

The policy sets rules for guarding against non-consensual sex and public displays such as masturbation that could offend other residents. It also requires that the Hebrew Home maintain regular staff orientation and training programs in resident sexuality.

Staff members are taught to monitor people known to be in intimate relationships — whether they involve simple handholding or intercourse — for signs that either party is uncomfortable.

For instance, disruptions in eating, sleeping or bathroom patterns could prompt a nurse to ask a resident whether she or he is unhappy in a relationship. Where a relationship seems unwanted, the home can take steps to help end it, from counseling an overly aggressive resident to moving one to a different floor.

The Hebrew Home has more than 250 beds assigned to residents with dementia. The home’s original policy acknowledged the sexual rights of those people while requiring, when one was known to be in an intimate relationship, that family be consulted. Staffers would counsel the family on the benefits of the relationship. If the family insisted on ending it, the home would comply.

In April, the Hebrew Home adjusted the policy to say that family members’ wishes wouldn’t necessarily be honored in all cases. Essentially, the home presumes that demented residents have the capacity to consent, absent evidence to the contrary, and works with families to accept the residents’ desires.

Even where a resident married to someone outside the facility has sex with another resident, the home could support the relationship if it’s healthy and consensual.

“This isn’t meant to be a hospital, it’s meant to be a home,” said Robin Dessel, 56, the Hebrew Home’s sexual rights educator. “A resident’s voice is foremost; it trumps everything.”

Nevertheless, law professor Tenenbaum said, “Since dementia is a progressive disease, the staff must be vigilant to ensure that a once-consensual relationship does not become abusive. It may be difficult to determine when a consensual relationship between demented nursing home residents becomes non-consensual.”

Tenenbaum said more nursing homes should emulate the Hebrew Home. She wrote in the Indiana Law Review that elderly care facilities could provide “do not disturb” signs; set policies to discourage the spread of sexually transmitted diseases; make condoms, vaginal lubricants and Viagra readily available; and provide beauty salons and other cosmetic services to help residents feel physically and sexually attractive.

Herzog, the octogenarian Hebrew Home resident, looked pretty in red lipstick and gold bangles on a recent visit. She said she’d love to have someone special in her life.

“You want to have someone to pat you, someone to hold hands with,” she said. “Age should not be a barrier to anything.”