Sleep and Hunger: Fruit Flies Reveal the Complicated Relationship Between Food and Drowsiness

When we're hungry, we have a harder time falling asleep. When we're full, though, we feel sleepy. In fact, it seems that sleep and eating are intertwined; people with sleep disorders such as insomnia, for example, often binge late at night. Now, scientists have discovered a little bit more about the complicated relationship between sleep and food.

In order to learn a little bit more about the link between sleep and food, the researchers examined fruit flies. More specifically, they examined sNPF, a neuropeptide long known to regulate food intake and metabolism. Now, it's also know to be an important component in regulating and promoting sleep.

In this case, the researchers activated sNPF in fruit flies. When they did, the flies fell asleep almost immediately, awaking only long enough to eat before nodding off again. In fact, the fruit flies were so sleepy that they snoozed right on top of their food source for days--rather like falling asleep on a giant hamburger bun and waking up long enough to take a few nibbles before falling back to sleep.

The next step was returning sNPF functions to normal. When the researchers managed this feat, the fruit flies resumed their normal levels of activity. This showed that sNPF has an important regulatory function in sleep in addition to its previously known function coordinating behaviors such as eating and metabolism.

"This paper provides a nice bridge between feeding behavior and sleep behavior with just a single molecule," said Nathan Donelson, one of the researchers, in a news release.

Neurons use neuropeptides to communicate a range of brain functions including learning, metabolism, memory and social behaviors. In fact, in humans Neuropeptide Y functions similarly to sNPF. However, scientists still don't fully understand how neuropeptide function at specific times and in specific cells affects sleeping in eating.

"Our paper makes a significant step into tying all these things together, and that is extremely important down the road to our understanding of human health." said Donelson in a news release.

The findings are published in the journal Neuron.