Bob Costas returns to NBC Monday

"Our long nightmare is over," NBC Olympics executive producer Jim Bell said from Sochi Monday, and with that, Bob Costas was headed back to his hosting duties after a six-day hiatus because of viral conjunctivitis.

Matt Lauer filled in for Costas for four of the six days, and Meredith Vieira for the other two.

Costas said during the worst of his absence he sat in a darkened hotel room in Sochi, with only brief breaks in the monotony to head to the hotel restaurant or to view the Black Sea from a balcony.

But early on NBC set him up with a feed to the network's various channels so he could follow the action. He also confessed to catching the end of the Syracuse-North Carolina game on ESPN. (Costas is a Syracuse alum.)

Costas said at the worst of the ailment light sensitivity and blurred vision made it impossible to work. "In terms of being able to function, I can function now," he said.

While he said he "would rather not feel this way for the rest of my life," he listed the current severity of his condition a 2 on a scale of 1-10.

Costas said his personal disappointment over missing nearly a week of the Games was not as disheartening as the thought he was not holding up his end of an operation in which so many colleagues are working so hard.

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"Your team takes the field for a big game, you want to be able to do your part of it," he said.

Costas said he was uncomfortable with the level of coverage his ailment got, but he said it is the nature of the high visibility of his role.

"This was viral, both literally and figuratively," he said.

Costas said doctors' initial diagnosis was that he had bacterial conjunctivitis, which would have cleared up far sooner than the viral kind, whose only cure is time.