Matthew McConaughey says downsizing his bed was the secret to strengthening his marriage with his wife Camila Alves.

The 55-year-old actor married Camila, 42, in 2012, with the pair marking their 13th wedding anniversary in June 2025.

Matthew, who has three children with Camila - Levi, 17, Vida, 15, and Livingston, 12 - reflected on the decision to downsize his bed in his new book Poems and Prayers, and repeated the advice during an interview with Fox News Digital.

He wrote: "The best thing you can / do for your / marriage. One way to surely / get ahead, / is get rid of that / king-size mattress, / and sleep in a / queen-size bed."

Speaking to Fox, Matthew explained how he came to the realisation.

He added: "We have kids and we go to our friend's house and he has one of these double king-size beds put together and all the kids sleep in the bed.

"The wife's on one side with her side table, and the husband's on the other side, and it's great when you got all three kids, but all of a sudden the kids get too big. They're out of the bed."

He continued: "I wake up one morning… I'm looking over there and Camila's like a football field away, man. Then you go to bed at night, like you want to snuggle up and… 'Well, we've got to cover you up. Come about 12 feet and I'll come 12 feet'."

The Interstellar star added he concluded that larger mattresses were "not good for the marriage, man". He said: "Get rid of that son of a b****. So we got a queen size where we're shoulder to shoulder. I'm telling you, it's good for your marriage."

He also noted the new arrangement leaves "no room" for their three children.

Matthew and Camila have previously spoken about how they manage disagreements.

In a joint interview in 2024 on the Your Mama's Kitchen podcast, the actor said: "Go and get something sweet. A sweet food.

"It can de-escalate some things, even if it's a nice piece of chocolate or some ice cream, it can de-escalate."