According to a fascinating recent study, this phenomenon would be caused by the activation of the endocannabinoid system, in a way analogous to the hunger associated with the consumption of cannabis.
Several studies have clearly shown that people who are sleep deprived show changes in their eating habits, including a more pronounced attraction to foods high in sugar and fat.
This increase in caloric intake is not insignificant when it occurs chronically, as it is associated with an increased risk of many metabolic disorders, including obesity, metabolic syndrome (a combination of hypertension, overweight and dyslipidemia) and type 2 diabetes. Given that approximately half of the population sleeps insufficiently (less than 7 hours per night) and/or has poor quality sleep, it is therefore very likely that this phenomenon contributes to the high incidence of overweight in the population, as well as many diseases that are associated with excess fat.
Lack of sleep: The same effects as cannabis on the feeling of hunger
The endocannabinoid system represents an excellent candidate to explain these effects of lack of sleep on the overconsumption of calories.
This system is best known for its role as a mediator of the psychotropic effects of cannabis: in fact, it is the specific interaction of the main constituents of cannabis (cannabidiol and Δ9-tetrahydrocannabinol) with certain receptors naturally present in the brain which is responsible for euphoria associated with the use of this drug.
However, the biological role of the endocannabinoid system goes far beyond its participation in these psychoactive effects: rather, it is a basic physiological mechanism that appeared very early in the evolution of animal life (it about 400 million years ago) and whose main function is to ensure the control of the metabolism, in particular everything related to the consumption of food (stimulation of the appetite) and the storage of calories.
This important role of endocannabinoids in appetite control also explains why cannabis use is generally associated with a significant increase in hunger in people who have used the drug, a property that is also used at medical purposes to stimulate the appetite in people affected by certain diseases (AIDS, cancer).
Lack of sleep: more cravings for fatty and sugary foods
To determine the possible involvement of the endocannabinoid system in the increased caloric intake of sleep-deficient people, a team of researchers subjected 30 volunteers to normal (7-9 h per night) or shortened (4 h per night) sleep episodes. night) and then examined their food choices when presented with a buffet containing a wide variety of foods.
They observed that people who had not slept enough had higher levels of certain endocannabinoids such as 2-oleoylglycerol (2-OG) than those whose sleep had been normal, and that they showed a clear preference for energy-dense foods (more calories per gram), such as donuts, sweet cookies, and chips.
Greater sensitivity to food odors
Examination of participants by functional magnetic resonance imaging suggests that this preference for high-calorie foods stems from certain changes in brain areas involved in the control of food intake. On the one hand, the researchers observed that the brains of sleep-deficient people show greater activity in the piriform cortex, an area involved in olfaction and which is very rich in receptors for endocannabinoids. Lack of sleep would therefore cause a greater receptivity to food odors and people who sleep insufficiently would therefore be more stimulated (and tempted) by the presence of food.
It should also be noted that this increase in olfactory activity occurs in conjunction with a disruption in the connectivity of the piriform cortex to the insula, the brain area that regulates calorie intake: people with high levels of cannabinoids therefore have less control over the quantities ingested, which would explain their attraction to fattier and sweeter foods.
Sleep is essential for good health
These observations therefore confirm that lack of sleep is not only harmful for our interaction with the outside world (loss of attention, irritability, reduced productivity), but also disrupts the functioning of our metabolism and can lead to an overconsumption of calories which, over time, promotes overweight and the development of a range of serious chronic diseases. Even though sleep is not very popular in our age when there is always something going on, 24 hours a day, seven days a week, this study reminds us that the fact remains that sleep is a time of stopping essential for the maintenance of good health.
Bhutani S: Olfactory connectivity mediates sleep-dependent food choices in humans Life 2019; 8: e49053.