The Lantern Corps of DC Comics saves people through shapes made from light. Each of them have powers imbued by light. But, in reality, what can light do? Funnily enough, just plain blue light can save the lives of sick and pre-term babies.
Those of you who have been reading DC Comics know that Green Lanterns aren't the only game in town anymore. A few years ago, other colored Lanterns were introduced, each associated with its own emotion. Red Lanterns were the corps of rage. Orange Lanterns were all about avarice. The Yellow Lantern Corps induced fear. And Blue Lanterns were the corps that were powered by eternal hope. Of course, the concept of Lanterns is silly, right? Light doesn't have any power, and what power it has isn't associated with any kind of emotion, right?
Well, the power of metaphor can go literal sometimes. Those of you who have seen the neonatal ward of a hospital have probably seen babies in little incubators, dark glasses over their tiny eyes, being bathed in blue light. There's a good symbol of hope, right there.
Just after birth, an infant's body has to switch gears in a lot of different ways. One of them is the breakdown of the red blood cells in its blood. Red blood cells don't last too long, and our liver has to rip them down and the body has to find a way to excrete them. While the infant is in the womb, its mother takes care of that. When it gets out, its own liver has to come online. It takes a while for any baby to do this, and so many develop a mild form of infant jaundice. The baby's skin turns yellowish from bilirubin, one of the biproducts of the process. A mild condition isn't problematic, but when a baby is born too early, or for some reason the liver doesn't kick in soon enough, the condition can lead to serious health problems.
Fortunately, the solution to most cases is what's called "bili lights." They give off light at 420 and 470 nanometers — blue light — that safely breaks down the bilirubin in the baby's blood. Infants are placed inside a clear incubator with as much skin showing as possible. Light shines down onto them. They're turned regularly, and their exposure time is monitored. This therapy helps them along until their livers are ready to do the job. Sure, if that doesn't work, further measures are taken to treat the jaundice. Still, it's simple blue light that keeps them healthy during this time. There aren't any special sonic frequencies. There isn't an unseen level of radiation. What's saving the baby is just, flat-out, the color blue.
It would be cool if actual Blue Lanterns showed up, though.