Can faking a smile make you feel happier?

When you're feeling down and don't have time for your typical pick-me-ups, you may follow the classic advice to fake a smile to trick yourself into happiness.

But can forcing a smile actually cheer you up?

The question has been controversial among scientists, Marie Cross, an assistant teaching professor of biobehavioral Health at Penn State, told Live Science. But in the past few years, research has revealed what she said feels like a clear answer: At least in a laboratory setting, making yourself smile can improve your mood.

A 2019 meta-analysis published in the journal Psychological Bulletin found that grinning could not only amplify happiness but create it.

"This is like the difference between smiling while looking at a picture of a puppy and smiling while staring at a blank wall," said Nicholas Coles, a research scientist at Stanford University who investigates emotions and lead author of the study. "It appeared that smiles could not only increase how happy you felt about the puppies but could also make you feel happy in an otherwise neutral context where you have no actual reason to feel happy."

Related: What happens in our brains when we 'hear' our own thoughts?

However, the meta-analysis findings weren't strong, Coles said, because it was based mostly on old, questionable research. "There's an analogy in meta-analysis called crap in, crap out. And unfortunately, you don't know if the previous evidence is crappy or not," he told Live Science, because you can't talk to the scientists who found it.