If you're looking to cut down on the amount of rubbish you eat, you should start by getting a good night's sleep.
That's according to a new study which found sleep deprivation increased the brain's sensitivity to food smells, making us far more likely to reach for unhealthy snacks and junk food.
The findings might explain why people who don't get enough sleep on a regular basis tend to eat more and gain weight, researchers said.
For the study, which was shared at the Cognitive Neuroscience Society's annual meeting in San Francisco, researchers analysed adults who had operated on just four hours of sleep.
The participants were asked to inhale food odours such as those from crisps and cinnamon rolls while undergoing MRI scans.
They were then asked to do the same experiment, but using non-food smells like fir trees.
A few weeks later, the same participants repeated the experiment having had eight hours sleep the night before.
When tired, participants showed greater brain activity in two areas involved in olfaction (the sense of smell) in response to food smells. When they were rested, this activity diminished.
Additionally, the spike in activity wasn't seen in response to non-food odours.
Researchers said the results highlight a role for "modulation in sleep-dependent appetite and eating behaviour".