You're listening to Shortwave from NPR.

Since I was a kid, one of my favorite things to do this time of year is to stroll around

neighborhoods looking at all the holiday lights.

They're just so romantic and full of irrepressible twinkling cheer.

But then something happened around a decade ago that made that twinkling a little less cheerful, at least for me.

I can still remember it clearly.

The first time I found myself staring at Christmas lights with LED light bulbs.

There was just something about the light that made my head spin, like the whole world was

jittery and off. Turns out it's a phenomenon called Flickr and I

wanted to understand how it works so I went to meet the Flickr Queen. You know I'd

rather be known as the Flickr goddess. But I didn't name myself so I'm stuck with

Flickr Queen.

Naomi Miller is a lighting scientist and designer at the Pacific Northwest National Laboratory.

She's been studying LEDs for nearly 20 years and she says flicker is a real problem for some people.

It may cause headaches or migraines.

Other people report nausea.

And we do know that people who have had traumatic brain injury in the past

seem to be more susceptible to problems from flickering LEDs.

It's unclear just how many people are bothered by Flickr,

but this is potentially a big problem because LED lights are the future.

The US government has been working for more than a decade to require that light bulbs become

more and more efficient, and it culminated in a regulation earlier this year that in effect banned the sale of most incandescent

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