In a scene from the hit TV show "Mad Men," Don Draper and Harry Crane go to White Castle for a late-night snack after a Rolling Stones concert.

Don watches in disgust as Harry downs 20 sliders and doesn't save any to bring to his family.

"Let them get their own," Harry says. "You bring home a bag of food and they go at it and there's nothing left for you. Eat first."

Harry may have thought he was looking out for himself, but he really was doing his kids a favor by preventing them from late-night eating fests, as well as tanking his own health. (He consumed about 2,800 calories and 120 grams of fat in that one sitting).

A new study from Spain published in the International Journal of Cancer looked at more than 4,000 people and found that those who ate their last meal before 9 p.m. (or at least two hours before they went to bed) had a 20 percent lower risk of breast or prostate cancer.

The researchers think that eating late boosts cancer risks because going to sleep soon after eating affects your ability to metabolize food — and that can trigger cancer-promoting inflammation.

They also suggest that it's no healthier to eat late and then push your natural bedtime later. Past research has found that disruption in circadian rhythm is also linked to a higher risk of cancer.

Research indicates that the ideal break between dinner and breakfast may be 13-plus hours.