Every mouse in its cage has its own internal clock. That clock tells it when to run, sleep, and eat. When food arrives at the same time every day, the clock keeps perfect time. When food shows up at random, the clock drifts, and the body ages faster. Scientists tested this on 528 mice: some were fed whenever they wanted, others only at night, when mice are active.
The nighttime eaters were split into two groups: one got food for 12 hours straight, the other for only 8 hours. It turned out that mice on the nighttime schedule put on less weight and became frail less often with age. And the males that ate for only 8 hours outlived them all: on average 916 days instead of 818. That's like a person living to 84 instead of 75.
Why does this work? When a mouse eats only at night, it starts eating less on its own, even when there's plenty of food. About 9-23% less. The body seems to relax: if food arrives on schedule, there's no need to stockpile fat for a rainy day. So this kind of regimen could help people who struggle to stick to a diet. All you have to do is skip late-evening and nighttime eating and shift your main meals to the daytime. Then your internal clock will run more precisely, and your body will ask for less food on its own.
Contrary to popular belief, in this experiment male mice outlived females: median lifespan was 818 days for males versus 694 for females. In mammals, females usually live longer, but in C57BL/6J mice the results are inconsistent. Perhaps the females were cold in individual cages without nesting material and spent more energy on heating.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.