Henry Dryer sits slumped over the tray attached to his wheelchair. He doesn't speak, and rarely moves, until a nursing home worker puts his headphones on.
Then Dryer's feet start to shuffle, his folded arms rock back and forth, and he sings out loud in perfect sync with his favorite songs.
"I feel a band of love, dreams," said Dryer, 92, who has dementia. "It gives me the feeling of love, romance!"
"There are a million and a half people in nursing homes in this country," director Michael Rossato-Bennett told ABC News. "When I saw what happened to Henry, whenever you see a human being awaken like that, it touches something deep inside you."
Alzheimer's disease is the most common cause of dementia, affecting 5.4 million Americans. The disease swiftly robs patients of their memories and other brain functions, forcing most to live out their final years in nursing homes.
Rossato-Bennett said he took on the documentary project to promote Music & Memory, a nonprofit organization that brings iPods with personalized music to dementia patients in nursing home care.
"When I end up in a nursing home, I'll want to have my music with me," said Dan Cohen, executive director of Music & Memory. "There aren't many things in nursing homes that are personally meaningful activities. Here's the one easy thing that has a significant impact."
Cohen said the personalized playlists, chosen by loved ones, make patients light up.
"They're more alert, more attentive, more cooperative, more engaged," he said. "Even if they can't recognize loved ones and they've stopped speaking, they hear music and they come alive."
Seizures landed Dryer in a nursing home 10 years ago. But he's always loved music, according to his daughter, Cheryl.
"He was always into music; always loved singing, dancing," she said. "He used to walk us down the street me and my brother and he would stop and do singing in the rain. He would have us jumping and swinging around poles."
Dryer's favorites: Cab Calloway; and Bing Crosby's "I'll Be Home for Christmas," which he sings in a soulful voice.
Dr. Oliver Sacks, a neurologist and author interviewed in the film, said music can have a powerful effect on people with dementia.
"We first see Henry inert, maybe depressed, unresponsive and almost unalive," said Sacks, whose account of music therapy in treating Parkinson's disease inspired the book and film "Awakenings." "Then he is given an iPod containing his favorite music. ... And immediately he lights up."
Geri Hall, a clinical nurse specialist at the Banner Alzheimer's Institute in Phoenix, said music activates a part of the brain that stays active despite dementia.
"There's something about music that cuts through right up until the very end of the disease," she said, adding that familiar music from the past can help people with dementia feel at home. "It calms them, it increases socialization, and it decreases the need for mood controlling medications."
But an iPod for every nursing home resident is no easy feat.
"That's a lot of money when you're talking about 200 people in a long term care center," she said.
Cohen's charity accepts new and used iPods and distributes them to nursing homes. He hopes "Alive Inside" inspires more people to think of music as a simple start for improving care for dementia patients.
"It's hard to see people idle," he said. "But we're all heading there, and I want to help create an environment that, when we get to a nursing home, feels like home."
"Alive Inside" premieres Wednesday April 18 at the Rubin Museum in New York City.