Story highlights John Noble's cult show "Fringe" is nearing the end of its run

Noble addressed his sleep disorder treatment, which briefly halted production

He's not as much of a junk food fan as his character; he recently discovered Twitter

Noble shared his prediction for the final episode: "A masterpiece"

After dealing with porcupine creatures, shape-shifters and planes full of crystallized bodies over five seasons, star John Noble is still having the time of his life on "Fringe."

The cult favorite sci-fi series is in the midst of its final season on Fox, and classic episodes premiere Tuesday night on the Science Channel.

Noble, who plays the brilliant (and occasionally mad) scientist Walter Bishop, recently spoke with CNN about his experience with the show and what fans can look forward to in the remaining episodes, leading up to a January 18 series finale.

CNN: Are you nearing the end of filming now?

Noble: My goodness, yes. We start filming our penultimate episode Tuesday morning. We're very close to the end, mate.

CNN: And what's that feeling like?

Noble: It just feels like an awful lot of work (laughs). We've still got a bit to do. It's an exciting thing feeling it all come together. There's a sense of closeness among the crew. We're here in Vancouver; it's our fourth year and, for the cast, our fifth year together. It's a bit odd. We are friends, so it's a bit sad.

CNN: Meanwhile, you're getting a second life on the Science Channel.

Noble: The thing about Science Channel is that they know "Fringe," and they love it. The people I know there have watched from the beginning. It's not just another product. They've brought people in to talk about the science of it. We're in a very good second home.

CNN: This season, do you feel that Walter is bearing the weight of a tremendous amount of pressure to put together this plan to fight the Observers?

Noble: Yes, but I think the pressure's on everyone. All the key players have to come to some sort of conclusion, and that's the gift of these last 13 episodes. Every character is under pressure, if you can call it that.

But it's a good journey. Every episode takes us further on the track to the finale. It's like writing a novel and having the chance to write the final chapter. The stakes are lifted every week for us. It's kind of exciting.

CNN: We've seen so many major twists just this season. What was your reaction to learning that Peter was going to utilize the tech of an Observer and sort of become one himself?

Noble: Well, it's pretty inspired, really. If you can't beat them, join them. Peter realized to combat these people, he would have to be on equal terms with them. It also gave Joshua Jackson a marvelous journey, which I think he's done splendidly.

The fun thing is that both men are struggling with their arrogance and hubris in different ways. It's a very interesting story arc to play as well. You have Walter not trying to be so smart and cruel, and Peter wanting to be more so. So that's playing out really well.

CNN: The show took a short break in shooting this season, as you had to take some time to take care of yourself. Are you doing better now?

Noble: I'm doing very well, mate. We decided we needed to address an ongoing issue, which been going on a long time for me, which is that I'm doing very well, mate. We decided we needed to address an ongoing issue, which been going on a long time for me, which is that I don't sleep . Ultimately, given the load of travel, I was starting to hit a wall. We did what we could to correct that. We probably really didn't need to take as much time as we did. The management was terrific and said, "Get it sorted out." We're still going strong at this stage, so something worked.

CNN: Have you enjoyed discovering Have you enjoyed discovering Twitter

Noble: I thought it was time I got with it. (Laughs) I resisted for so long. I have no idea, to be honest, what I'm doing. I just go on every once in a while and say something, and it gets retweeted 6,000 times.

It's an astonishing way of communicating. Thank God for that, because it takes away the tyranny of those who would withhold information.

I remember I tweeted, "Just saying g'bye to Georgina Haig. Lovely woman!" I just had afternoon tea with Georgina (whose character died in a recent episode). That was taken as, she's gone forever. At that stage, she was still on the show, so I thought "What have I done?" I knew she was gone! You've gotta be careful! (Laughs)

CNN: Walter is famous for his love of junk food. Do you have a favorite junk food on or off set?

Noble: To survive, I try not to eat junk food. I hate to destroy the myth!

On a film set, if you eat junk food, you'd finish around 400 pounds at the end of the first season. That's just the nature of the work.

To destroy another myth, we don't actually eat it, because we can't. In 40 takes, you'd be absolutely bloated with Red Vines or whatever else you're having. We go through the motions of it and then have to get rid of it to so we can do another take.

There was a bacon sandwich I thought was rather nice ...

CNN: And what can fans expect as it comes to a close?

Noble: I haven't read the final episode yet, but I know that (executive producer) Joel Wyman has put everything, and I mean everything, he's got into this. He's directing the last episode. I think it will be a masterpiece. I haven't read it, but I can't imagine anything less with the amount of heart he's put into it. Fingers crossed, but that's my prediction. I think it will be a masterpiece.