Bruce Willis "forgot how much fun" taking care of babies was until his daughter arrived.

The Hollywood hardman and his spouse Emma Heming Willis welcomed Mabel into the world on April 1. Bruce is also father to daughters with ex-wife Demi Moore - Rumer, 23, Scout, 20 and 18-year-old Tallulah.

Bruce hasn't taken care of a baby in nearly two decades until recently, but is finding the experience remarkably pleasurable.

"You just forget how much fun it is and how cool it is," Bruce told Entertainment Tonight. "There are a lot of things that I'm reminded of that regular life knocks out of you."

Bruce hasn't been getting any sleep as he's been up looking after Mabel.

The actor loves cradling his daughter throughout the night despite his somnolence.

"I didn't get to bed till 9am," Bruce revealed. "[Lately] I'm just up wandering around with her It just calms you down. It calms me down, anyway."

Bruce and Emma tied in the knot in 2009.