Robin Roberts Gets Laughs on 'Letterman'
The "GMA" co-host paid a visit to "Late Night" to discuss her new book, "Everybody's Got Something."

Rodents are the workhorses of biomedical labs. So it's important to know if they're stressed out, which could affect results. Now we know that lab rodents may be regularly exposed to a big stressor, men.
Researchers noticed that mice showed a lower pain response, a sign of stress, when the human was present. So they put mice and rats in the clear cubicles where their faces were visible and injected them with an irritant. The rodents expressed pain through grimacing when no humans were nearby. But when confronted with a male researcher or even just his odiriferous T-shirt, the animals grimaced less.
Female observers did not get the same rodent reaction. Turns out that smelling a human male made rodents produce higher level of stress hormone and increase their body temperature. That stress response also blunted their sensitivity to pain. The study is in the Journal Nature Methods.
Researchers may have to come up with ways to ward off the stress effects of male researchers. Because to a rodent, men smell like hell.
As you may have heard, Robert's got a great new book, it's called "Everybody's Got Something." And last night, it was letterman who got Robin. She stayed up way past her bed time for evening appearance, special appearance.
When I got outside of, or I'm gonna still be here. It is fascinating what they are able to do is completely deplete your immune system to the brink. And then my dear sister Sally, she had healthy stem cells that were compatible and she was a perfect match so they insert her cells into me and I am assent you are sitting here not just with me but with my sister as well.
We try to get your sister, but she's on the Fallon. Nothing works here.
A little joke there at the end Robin, but David was pretty serious about getting his medical stuff.
He is really into that, you know, because he had his own health concerns. And it was a facinating conversation kind of took me off out a little bit, but lovely everyone around there was, it was different, and I really enjoyed it, and I was up way past my bed time. He's one of good guys, he really is.