Just as Elizabeth Vargas returns to ABC's 20/20 after taking time off for Alcohol rehab, "Nightline" Anchor Dan Harris is breaking the news of that cocaine and Ecstasy use drove him to a highly embarrassing on-air panic attack in 2004.

The NY Daily News says that the TV journalism veteran came clean Tuesday about the abrupt meltdown in front of 5 million viewers as a fill-in news anchor on "Good Morning America," when then-hosts Diane Sawyer and Charlie Gibson turned the cameras over to Harris for the start of the 7 a.m. newscast.

"I was overtaken by a massive, irresistible blast of fear," Harris, 42, wrote on the ABC News blog early Tuesday, "It felt like the world was ending. My heart was thumping. I was gasping for air. I had pretty much lost the ability to speak.

"And all of it was compounded by the knowledge that my freak-out was being broadcast live on national television."

Harris says his drug use began a year earlier after a six-year tour of duty covering wars in Afghanistan, Israel, the Palestinian territories and Iraq.

"I became depressed. In an act of towering stupidity, I began to self-medicate," says Harris, who is still a weekend correspondent on ”GMA.”

Shortly after the career-endangering episode, Harris' boss and mentor, Peter Jennings, assigned him the religion beat. While covering all aspects of faith for ABC News, including his famous interview with disgraced former pastor Ted Haggard, Harris stumbled on meditation as the Rx for his personal problems.

Insisting that he still has "an allergy to all things touchy-feely and New Age-y," Harris credits the relaxation techniques with turning his life around.