Jessica Alba thinks "communication" is key to a happy marriage.

The 42-year-old actress has been married to Cash Warren since 2008, and Jessica has revealed the real secret to their romance.

The Hollywood star - who has Honor, 15, Haven, 12, and Hayes, five, with her husband - told 'Entertainment Tonight': "I think sometimes it's over communication, sometimes it's under communication.

"Sometimes it's, 'I need my space I'll talk to you [later].' When I need [you, I'll say], 'I miss you, will you come back?' [It's about] always communicating how you feel."

Despite this, Cash recently admitted that their romance isn't always easy.

The 44-year-old producer conceded that their relationship goes through "cycles".

During an appearance on the 'Whine Down' podcast, Cash shared: "You can go months when your energy is just off. It's not like you're actively fighting over those months, but your energy is off. Just having the patience to know that eventually it starts to come back together and your energy starts to get back aligned.

"Going through a few of those cycles, I no longer get as nervous and kind of start looking at the door. I no longer get as nervous when you're drifting apart or your energy's off."

Cash and Jessica have developed a really good understanding of each other over time.

The producer explained that the loved-up couple have different ways of resolving their issues.

He said: "She's aligned there, so when we're going through those times we either give each other the space that we need, we talk it out, we maybe go on a date night.

"You try to do things to get it back. Fortunately I've got a partner who's kind of right there lock and step."