"There is an awareness that I really struggled with, particularly in my late teens, when I was going out to places for the first time where you would feel -- again, it could have largely been in my head, but -- you would feel watched when you went into a bar, when you went into a pub," Radcliffe recalled.
"Then, in my case, the quickest way of forgetting about the fact that you were being watched was to get very drunk and then as you get very drunk, you become aware that, oh, people are watching more now because now I'm getting very drunk, so I should probably drink more to ignore that more," he said.
Radcliffe played the title character in all eight Harry Potter films. He said he can empathize with other young stars, such as singer Justin Bieber, when they appear to act out.
"There is no blueprint for starting young and working stuff out," the star said. "That's why, like, whenever people, like, have a go at Justin Bieber drag racing cars, whatever, I'm always like, 'Yeah, but you know. I don't know. Stuff could be super crazy for him right now.'"
"You don't quite know how overwhelmed it's possible to get," he explained. "Part of the thing is the expectation that you just be delighted all the time. You have a great job, you're wealthy. You don't have a right to ever feel sad or to not be excited about the whole thing all the time."
Radcliffe was 12 years old when the first Harry Potter movie, Harry Potter and the Sorcerer's Stone, opened in theaters. He told IGN this month he wouldn't be surprised if the franchise reboots with a new set of young actors.
"I'm sure there will be come other version of it; I know I'm not the last Harry Potter I'm gonna see in my lifetime," the actor said.
"It will be interesting to see how long those films stay... it feels like there's a sacredness around them at the moment, but that'll go, the shine will wear off at some point," he added. "It'll be interesting if they reboot them and just do the films again or do a series; I'm fascinated to watch."
Radcliffe stars in the new TBS series Miracle Workers and will also star in the upcoming movie Guns Akimbo.