Does Lack of Sleep Dysregulate Parts of Our Brain that Control Appetite?

• A study published in Nature Communications sought to identify the brain mechanism through which a lack of sleep increases food desire.
• They found that a lack of sleep decreases the activity of cortex regions responsible for cognitive processes regarding food intake while increasing the activity of the subcortical amygdala region.
• Loss of sleep leads to a heightened desire for high-calorie foods.

When lacking sleep, some drink coffee, some try to increase their physical activity to stay awake, and some visit the fridge. Most people have experienced this situation when they couldn’t get enough sleep, accompanied by a desire to eat more food than usual. But does lack of sleep really increase our appetite?

Sleep and appetite

Researchers extensively investigated the link between sleep and the desire to eat. Many found that insufficient sleep is associated with increased food intake. A 2008 meta-analysis of 30 studies found that short sleepers, people spending below-average time asleep, are more likely to be overweight and obese. This association was present in adults and children (Cappuccio et al., 2008). A newer meta-analysis confirmed these findings again, showing that short sleep duration leads to an increased risk of obesity later in life (Bacaro et al., 2020) (see Figure 1).

 

Figure 1. Sleep and obesity

 

Similarly, newer studies showed that people who eat at night, at the time when they should be sleeping, were more likely to be overweight or obese. They also consumed sugar-sweetened beverages more often and ate fruits and vegetables less often than those not prone to eating at night (Lent et al., 2022). Additionally, individuals suffering from night eating syndrome, a condition in which they tend to eat lots of food at night, have a lower quality of sleep than those without this disorder (Tzischinsky et al., 2021).

One experiment showed that individuals who slept only 4 hours at night ate 22% more calories for breakfast the following day and felt hungrier immediately before breakfast (Brondel et al., 2010)(see Figure 2).

 

Figure 2. Sleep and food intake behaviors

 

Despite all the evidence that the desire for food and sleep quality are connected, the neural mechanisms that produce this effect remained more or less unknown (Greer et al., 2013).

The current study

Study author Stephanie Greer and her colleagues wanted to identify the neural mechanism through which a lack of sleep increases the desire for food. They wanted to know what changes in the brain when we lack sleep produce this effect.

These authors conducted a neuroimaging study in which they focused on a set of cortical and subcortical regions of the brain that researchers consider crucial for evaluating food stimuli and regulating the desire for food. These areas were the anterior insular cortex, lateral orbital frontal cortex, and anterior cingulate cortex in the brain’s cortex. All of these areas have well-established roles in signaling the value of a food stimulus and regulating how we integrate evaluations of various food features to create preferences for food. Studies have also shown that the functioning of these areas of the cortex is disrupted when an individual lacks sleep (Muzur et al., 2002).

On the subcortical level, they focused on the amygdala and the ventral striatum regions. Previous studies showed that the amygdala is very reactive to food stimuli. Activity in the ventral striatum, on the other hand, very precisely predicts immediate food intake, binge eating, and weight gain (Greer et al., 2013) (see Figure 3).

 

Figure 3. Neuroimaging study of various brain regions

 

The procedure

The study participants were 23 young adults, the average age of whom was 21. Of these, 13 were females. Their mean body mass index was 23, meaning that, on average, they were normal weight.

Participants completed two experimental sessions. During one session, they spent a night of normal sleep in the study authors’ lab, monitored by polysomnography equipment. The second session was a night without sleep in the same lab, monitored by lab personnel and wrist actigraphy.

Wrist actigraphs are wearable devices that measure movements. Researchers can use them to determine when the wearer is sleeping and when he/she is awake. Polysomnography equipment consists of a set of devices used to record various physiological parameters during sleep. These can include brain waves (EEG), eye movements, muscle activity, heart rate, and breathing patterns. Polysomnography is used to monitor sleep quality and diagnose sleep disorders.

Study participants underwent functional magnetic resonance imaging (fMRI)  the morning after the experimental night (see Figure 4).

 

Figure 4. Procedure (Greer et al., 2013)

 

Sleep deprivation reduced activity in the studied cortical regions

Results showed that brain activity was reduced after the night without sleep in all three studied areas of the cortex – the anterior cingulate cortex, the lateral orbital frontal cortex, and the anterior insular cortex.

In contrast to the cortical regions, the amygdala region became much more responsive to desirable food items after sleepless nights than when participants slept normally. The ventral striatum activity did not differ between the two experimental nights (see Figure 5).

 

Figure 5. Increased amygdala responsiveness to desirable food after reduced sleep

 

Sleep deprivation increases the desirability of high-calorie foods

Compared to the night when they normally slept, study participants expressed higher levels of desire for high-calorie foods after the night without sleep. There was no difference between the two nights in how much participants desired low-calorie items. Overall, the increase in desire for specific foods represented a desire to eat an additional 600 calories after the night without sleep. The increase in desire for high-calorie foods was so specific that the increase in the desirability of a specific food item after a night without sleep could be predicted based on its calorie content (see Figure 6).

 

Figure 6. Sleep deprivation and high-calorie food desirability

 

Conclusion

Overall, the study found that lack of sleep decreases the activity of the cortex areas responsible for cognitive processes regarding food while increasing the activity of the amygdala subcortical region. After a sleepless night, high-calorie food items also became more desirable.

These findings contribute to a better scientific understanding of the neural mechanisms underpinning the link between sleep deprivation and increased desire for food. They very strongly suggest that weight loss and obesity prevention programs should consider sleep quality and include regulating any sleep problems among their goals.

The paper “The impact of sleep deprivation on food desire in the human brain” was authored by Stephanie M. Greer, Andrea N. Goldstein, and Matthew P. Walker.

 

References

 

Bacaro, V., Ballesio, A., Cerolini, S., Vacca, M., Poggiogalle, E., Donini, L. M., Lucidi, F., & Lombardo, C. (2020). Sleep duration and obesity in adulthood: An updated systematic review and meta-analysis. Obesity Research & Clinical Practice, 14(4), 301–309. https://doi.org/10.1016/j.orcp.2020.03.004

Brondel, L., Romer, M. A., Nougues, P. M., Touyarou, P., & Davenne, D. (2010). Acute partial sleep deprivation increases food intake in healthy men. The American Journal of Clinical Nutrition, 91(6), 1550–1559. https://doi.org/10.3945/ajcn.2009.28523

Cappuccio, F. P., Taggart, F. M., Kandala, N.-B., Currie, A., ChB, M., Peile, E., & Miller, M. A. (2008). Meta-Analysis of Short Sleep Duration and Obesity in Children and Adults. 31(5).

Greer, S. M., Goldstein, A. N., & Walker, M. P. (2013). The impact of sleep deprivation on food desire in the human brain. Nature Communications, 4. https://doi.org/10.1038/ncomms3259

Lent, M. R., Atwood, M., Bennett, W. L., Woolf, T. B., Martin, L., Zhao, D., Goheer, A. A., Song, S., McTigue, K. M., Lehmann, H. P., Holzhauer, K., & Coughlin, J. W. (2022). Night eating, weight, and health behaviors in adults participating in the Daily24 study. Eating Behaviors, 45. https://doi.org/10.1016/j.eatbeh.2022.101605

Muzur, A., Pace-Schott, E. F., & Hobson, J. A. (2002). The prefrontal cortex in sleep. Trends in Cognitive Sciences, 6(11), 475–481. https://doi.org/10.1016/S1364-6613(02)01992-7

Tzischinsky, O., Latzer, I. T., Alon, S., & Latzer, Y. (2021). Sleep quality and eating disorder-related psychopathologies in patients with night eating syndrome and binge eating disorders. Journal of Clinical Medicine, 10(19). https://doi.org/10.3390/jcm10194613