Gwyneth Paltrow says a good night's sleep is essential to looking good.

The Oscar-winning actress - who has two children, Apple, seven, and five-year-old Moses with husband Chris Martin - admits if she doesn't get a lot of rest, it shows in her appearance.

She said: "For me, sleep is a major thing. I don't always get it, and when I don't, I look like I've been hit by a truck."

Gwyneth also credits drinking lots of water, taking vitamins "religiously" and having at least one cup of coffee - with almond milk - each morning to help maintain her youthful looks.

The 39-year-old beauty detoxes twice a year and is a fan of the Clean Program, an elimination diet that lasts for three weeks and allows a daily lunch.

She told 'Ask Dr. Brandt' on Sirius XM Radio: "I find it very rejuvenating. It's like being high."

Gwyneth - who credits celebrity trainer Tracy Anderson with her amazing figure - has previously said she doesn't like to diet and eats what she likes because she exercises so much.

She said: "I had to work hard to get it like this, but now I'm here it's so great because I don't have to think about it. I can just enjoy life. What a relief is that.