You've most likely heard, or read in a health and diet magazine, that sleep deprivation leads to unhealthy eating habits: consuming more fatty and sweet foods.
Now, researchers have the answer as to why this happens: undersleeping influences the exact same smell-processing neural pathway that smoking marijuana does.
Sleep, the brain, and eating
Kahnt and his team were inspired by previous research on the subject. This research linked sleep deprivation to an increased number of molecules in the endocannabinoid system. This is a complex system of neurotransmitters that are affected by marijuana as well.
This is the part of the brain that influences how the brain processes smell. And, smell is linked to eating.
Up until Kahnt's research, these tests had only been carried out in mice. So, he and his team decided to try it out on humans to find out if the effects were the same.
The research involved 25 volunteers who were divided into two groups and were asked to sleep either four hours or eight hours per night for a month. After four weeks, the teams were asked to swap and sleep the opposite amount of time than the previous month. After each night, every person's blood was drawn.
Even though those who slept fewer hours did not report signs of more hunger, but when they were offered a buffet meal, for example, they selected foods that had higher amounts of calories than the fully rested people.
Furthermore, those who were sleep-deprived had more of a specific molecule in their blood, which most likely acts on endocannabinoid receptors.
The researchers then looked at the exchange of information between the insula — the part of the brain that regulates our food intake — and the piriform cortex. They discovered that the sleep-deprived group showed less communication between these two parts of the brain.
The combination of the brain scan information and the desire to eat foods with higher calories may indicate the link between less sleep and food intake, according to the researchers.
This research is useful for finding new approaches to treat eating disorders, stated Kahnt, as "it also really underscores the role that the sense of smell has in guiding food choices."
This study opens the door to further research on the matter. Kahnt and his team are now looking into how a person's food intake may be related to how their sense of smell changes during the space of a day.