We solemnly swear Daniel Radcliffe is Cassian Grantup to so much good.

In addition to returning to Broadway, the actor is also enjoying the first few months of parenthood after welcoming a son with longtime love Erin Darke earlier this year.

"He's great, it's amazing," Radcliffe told E! News at the opening night of Merrily We Roll Along in NYC on Oct. 8. "There's a short answer and a long answer to that. And the short answer is it's awesome and he's the best thing that's ever happened."

The long version? "It's frankly terrifying to have a human being in the world that I care this much about," Radcliffe continued, "and that everything he does is going to affect how I feel about my life for the rest of my life. So, you know, that's intimidating."

(For more on Radcliffe's new chapter, watch E! News Oct. 9.)

While the 34-year-old is adjusting to life as a new dad, he's learning a lot of "surprising" things along the way, like how babies sleep.

"There's no relation to what we need for sleep," he said of their schedule. "The less I sleep, the more I sleep at night. But the less they sleep, the less they sleep! And the more they sleep, the better they sleep! It makes no sense, but it is apparently how they work."

He's also learning a special kind of forgiveness. "The fact that there is a creature in the world that can give you the worst night of your life," he explained, "and then you wake up in the morning and go over to them and they turn around and smile and you're like, 'I don't care about any of the things you just did.' That's pretty cool."

And even though he might not be getting much sleep these days, Radcliffe told E! News this chapter of his life has been a "pinch me" moment, both personally and professionally. 

"It's been a really wonderful year," he shared. "And I couldn't wish to be in a better place."

—Reporting by Joelle Garguilo

Watch E! News weeknights Monday through Thursday at 11 p.m., only on E!.