(CNN) -- Sleeping in Earth's orbit, floating balls of water, and the future of "average citizens" in space were among the topics of a live CNN interview Monday with astronaut John Glenn from the shuttle Discovery.

Glenn and Commander Curt Brown took time out from their mission to talk with CNN's Miles O'Brien and Walter Cronkite.

NASA scheduled some time off for the Discovery crew Monday, and Glenn said he mixed in a little work with a little play.

"We did do things like make balls of water that can float out in front of you and inject them with bubbles and all sort of things like that. They are very unusual," he said.

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But Glenn said he also used his free time to work on a cognition experiment, which measures reaction time in space compared with tests run previously on the ground.

Glenn said he felt that he did well on the test, but would have to wait for the final results to be sure. He also said he enjoyed having "a little more relaxed day up here."

Better night's rest

Cronkite asked Glenn how he had slept the previous night, and Glenn said he actually got more sleep than normal.

"It is easier to sleep here than it is on the ground when you have that headnet on and you have some 21 leads coming off your body," Glenn said, referring to the equipment he is wearing to monitor his body while he sleeps.

It is easier to sleep in orbit, he said, "because there are no pressure points up here."

Glenn and Brown also took questions submitted by viewers through CNN Interactive.

One man asked if "average citizens" would be going into space any time soon.

That may happen in the "not too distant future," Glenn said, but it may be a while because the missions are very expensive and focused on science.

"The major reason we have these things is to do basic research up here and not just provide spots to ride," he said.

This mission alone has 83 experiments, "many of them right out there on the cutting edge of science," Glenn said.

At the beginning of the interview, Glenn and Brown offered a tribute to late CNN Space Correspondent John Holliman, who died in an auto accident in September.

Holding up a photo of Holliman, Brown said, "We would like to thank John for all the things that he has done for our space program, and we would like to say that he will always be in our hearts."