Sleep deprivation makes it harder to resist unhealthy foods, according to a new US study.
Researchers at Northwestern University, Chicago, found that not getting enough sleep sparks production of the hormones endocannabinoids, which affect food cravings and how smells are processed, making unhealthy snacks – such as biscuits, crisps and fried food – more appealing.
Studies on mice found that endocannabinoids increase food intake by influencing how food smells are processed.
Scientists at the university conducted experiments in 29 men and women, aged between 18 and 40.
Divided into two groups, the first group achieved a healthy eight hours of sleep for four weeks before being disturbed frequently during the night during the second four weeks of the study. The second group did the experiment the opposite way around.
After sleep, scientists presented participants with a healthy breakfast, lunch and dinner alongside a buffet of less healthy food, with their choices monitored.
Leading the study, Professor Thorsten Kahnt said: “We put all this together and asked if changes in food intake after sleep deprivation are related to how the brain responds to food odours – and whether this is due to changes in endocannabinoids.”
He explained: “We found participants changed their food choices. After being sleep deprived, they ate food with higher energy density like doughnuts, chocolate chip cookies and potato chips.”
Previous studies suggests endocannabinoids may impact how neurons work in the paths between the nose and brain.
Northwestern University’s drew participants’ blood to check which endocannabinoid molecules were present, finding levels of a molecule called 2OG were elevated after sleep deprivation.
When those people were given the choice to eat whatever they liked, those with greater levels of 2OG ate food higher in calories.
Professor Hahnt added: “It might be worth taking a detour to avoid your local doughnut shop next time you catch a 6am flight.
“When you’re sleep deprived these brain areas may not be getting enough information. You’re overcompensating by choosing food with a richer energy signal.”