He gave Mr. Carson a tremor — but behind the scenes, Julian Fellowes was the one shaking.

The “Downton Abbey” creator recently opened up about how he’s overcoming a supposedly “incurable” condition that made everyday tasks nearly impossible, thanks to a “terrifying” yet “revolutionary” procedure.

“You’re kept awake the whole time,” Fellowes, 76, said in a new video with Insightec, which documents his journey to treat a little-known neurological disorder that affects an estimated 1 in 5 adults over the age of 65.

What condition does Julian Fellowes have?

It’s called an essential tremor, a nervous system disorder that causes uncontrollable, rhythmic shaking. It can strike almost any part of the body but most often hits the hands, arms, head and voice, according to the Mayo Clinic.

Often confused with Parkinson’s disease, essential tremors flare up during movement — like lifting a cup or writing. Parkinson’s shakes tend to be most prevalent when the body is at rest.