In March 2020, Dr. Robert Kadlec addressed a House committee to confirm his role and responsibilities as the federal government's top preparedness official coordinating the government's COVID-19 response.

As assistant secretary for preparedness and response at the Department of Health and Human Services , Kadlec offered a lengthy statement to lawmakers on the "four principal functions" of his role.

None of those functions involved downplaying without scientific evidence a theory that the virus emerged from a laboratory in the Wuhan Institute of Virology. But that's what Kadlec now says he did by assisting Dr. Anthony Fauci, America's former top infectious diseases adviser, in his effort to suppress the lab leak theory.

Kadlec says it's a decision that keeps him up at night. Literally.

"I wake up at usually about 2 or 3 a.m. and think about it honestly, because it's something that we all played a role in," Kadlec told Sky News in an exclusive interview.