Harry Styles fell asleep ''while floating'' during the filming of 'Dunkirk'.

The 23-year-old singer makes his acting debut in the new Christopher Nolan-directed World War Two drama - but has admitted to nodding off between the breaks in filming.

Harry shared: ''I slept most of ... I'd say 90 percent of what wasn't filming, I was asleep.''

And the One Direction star revealed he found some unusual places to catch up on his sleep during the shoot.

He told PEOPLE: ''Boats, sides of boats, swimming ... I definitely fell asleep while floating a couple times. It was nice, good, refreshing.''

Harry appears alongside a star-studded cast in the war movie, which also features Sir Kenneth Branagh, Tom Hardy and Mark Rylance.

He pointed out that, because much of the movie was filmed at sea, it wasn't as glamorous as people might assume.

But Harry explained: ''There were a couple days when we were just out in the water all day that felt like they were the most rewarding days when they were done.

''During they were the worst days, but as soon you get home and shower it was the most rewarding part of the thing.''

Meanwhile, Harry recently revealed he cried when he first watched 'Dunkirk'.

The chart-topping Brit - who plays the role of a soldier during the evacuation of Dunkirk - admitted he was overcome with emotion when he saw himself in action at the film's premiere in London last week.

Harry said: ''The first time I watched it, because I hadn't seen anything and how he'd put the story together, I was more watching to see how the story was, and when I watched it at the premiere in London it got me a couple of times.

''There were a couple of emotional bits but I didn't know if I was allowed to cry at a film I'm in, but yeah it was really emotional. It's a very personal experience, even if you're watching it in a cinema full of people you feel like you're watching it on your own.''