From Nature:
Your stomach may truly have a mind of its own. A tiny area of the brain may switch sleep schedules to match up with mealtimes. It’s been known for a long time that nocturnal creatures such as mice and bats flip their sleep schedules if food is only available during the day. But finding the parts of the brain responsible for the switch has proved difficult.
In a paper published today in Science, a team led by Clifford Saper from Harvard Medical School in Boston, Massachusetts suggests they have found the region of the brain responsible for the sleep-rhythm adjustment — a clump of cells known as the dorsomedial hypothalamic nucleus (DMH). This region sits close to the area of the brain that manages ordinary circadian responses to light and dark. The study shows that mice lacking a particular gene that acts in the DMH do not adjust to changes in feeding schedule. Reinstating the gene restored the behaviour.
More here.