King Charles’ nighttime routine revealed — Why up at 4 a.m.?

King Charles’ daily routine may sound a little different than the average menfolk, but after all, he is the monarch of the United Kingdom.

Actress Sophie Winkleman — who is married to Lord Frederick Windsor, the son of the late Queen Elizabeth’s first cousin Prince Michael of Kent — shed some light on the 75-year-old sovereign’s habits.

The “Two and a Half Men” star, 43, called Charles a “very dear friend” in a new interview with Tatler.

“I spend a bit of time with him,” she shared.

She explained that the former Prince of Wales often stays up late writing letters after the work day of carrying out royal engagements is done.

The “Sanditon” actress continued: “You see how he works all day long, has a quick supper and then disappears until about 4 a.m. to write letters. He cares about so many things, and he comes up with brilliant solutions.”

She added that she’s “really good friends with all” members of the royal family, calling them “fun, clever, kind people” when they are “behind the camera.”

Winkleman then gave some insight into the ones in the Firm whom she is the closest to, including Sophie, the Duchess of Edinburgh, Princess Beatrice, Princess Eugenie, Zara Tindall, Princess Anne, Sarah Ferguson and Princess Margaret’s daughter Sarah Chatto.

She is also a big fan of Prince William and Kate Middleton, however, “they’re so busy and don’t live in London, so I don’t see them much.” The couple currently live in Windsor.

Winkleman most recently made an appearance at the Duchess of Cambridge’s Christmas carol concert at Westminster Abbey earlier this month.

Her 10-year-old daughter, Maud, also used to go the same school as Middleton and William’s kids, Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5.

In the 2015 Amazon Prime documentary “Serving the Royals: Inside the Firm,” Charles’ wild daily list of demands were unveiled.

Princess Diana’s former butler Paul Burrell revealed that Charles’ staff are given strict instructions to care for him, as “everything [has to be] done for him.” 

“His pajamas are pressed every morning, his shoelaces are pressed flat with an iron, the bath plug has to be in a certain position, and the water temperature has to be just tepid” in a bathtub filled “only half full,” Burrell said in the documentary.

The ruler even “has his valets squeeze one inch of toothpaste onto his toothbrush every morning.”

For breakfast, Charles munches on homemade bread, a bowl of fresh fruit and fresh fruit juices.

Although, when he has to travel, a “breakfast box” must go with him — including six types of honey and mueslis.