CHICAGO -- A volunteer slips her arms into a gauzy yellow hospital gown and approaches a medical crib holding a tiny newborn hooked up to noisy machines.
"OK," she says, with a smile. "Baby time."
That means cuddle time in the neonatal intensive care unit at the University of Chicago's Comer Children's Hospital, where, as at several other hospitals around the country, strangers offer a simple yet powerful service for newborns too tiny or sick to go home.
When nurses are swamped with other patients and parents cannot make it to the hospital, grandmas, empty-nesters, college students and other volunteers step in. They hold the babies, swaddle them, sing and coo to them, rock them, and treat them as if they were their own.
"You can see them calm, you can see their heart rate drop, you can see their little brows relax," said Kathleen Jones, 52, a cuddler at the Chicago hospital. "They're fighting so hard and they're undergoing all this medical drama and trauma. My heart breaks for them a little bit."
Newborn intensive care units are noisy, stressful environments. There are babies born extremely prematurely, or with birth defects and other illnesses. Some are too sick to be held -- but not too sick to touch. Cuddlers reach a finger inside their incubators and stroke tiny bare bellies.
Scientific evidence on benefits of cuddling programs is scarce, but the benefits of human touch are well-known.
In one study, gentle caressing or placing a hand on preterm infants reduced levels of stress hormones. Other recent studies have suggested touch may benefit preemies' heart rates and sleep and perhaps even shorten their hospital stays.
Studies also suggest that early negative experiences -- including pain, stress and separation from other humans -- may hamper brain development, while research in animals shows that positive interactions enhance brain growth, said Jerry Schwartz, medical director of medical neonatology at Torrance Memorial Medical Center near Los Angeles.
The benefit "at the most superficial level" is obvious, he said. "A baby is crying, mom's not there, the nurse is busy with other sick babies, and it's an unpleasant life experience to be crying and unattended to, and, voila! A cuddler comes over and the baby stops crying."
Parents typically must consent for their babies to be part of cuddling programs, and cuddlers must undergo background checks and training before starting the job.