Sleep restriction increases the neuronal response to unhealthy food in normal-weight individuals

Abstract

Context: Sleep restriction alters responses to food. However, the underlying neural mechanisms for this effect are not well understood.

Objective: The purpose of this study was to determine whether there is a neural system that is preferentially activated in response to unhealthy compared with healthy foods.

Participants: Twenty-five normal-weight individuals, who normally slept 7-9 h per night, completed both phases of this randomized controlled study.

Intervention: Each participant was tested after a period of five nights of either 4 or 9 h in bed. Functional magnetic resonance imaging (fMRI) was performed in the fasted state, presenting healthy and unhealthy food stimuli and objects in a block design. Neuronal responses to unhealthy, relative to healthy food stimuli after each sleep period were assessed and compared.

Results: After a period of restricted sleep, viewing unhealthy foods led to greater activation in the superior and middle temporal gyri, middle and superior frontal gyri, left inferior parietal lobule, orbitofrontal cortex, and right insula compared with healthy foods. These same stimuli presented after a period of habitual sleep did not produce marked activity patterns specific to unhealthy foods. Further, food intake during restricted sleep increased in association with a relative decrease in brain oxygenation level-dependent (BOLD) activity observed in the right insula.

Conclusion: This inverse relationship between insula activity and food intake and enhanced activation in brain reward and food-sensitive centers in response to unhealthy foods provides a model of neuronal mechanisms relating short sleep duration to obesity.

Trial registration: ClinicalTrials.gov NCT00935402.

Conflict of interest statement

Conflict of Interest: The authors declare no conflict of interest.

Figures

Figure 1

Brain regions in normal-weight men and women (n=25) with higher activation when exposed to unhealthy>healthy food following restricted (a) and habitual (b) sleep are represented in color. Brain left is image left. Brain regions were considered significant with an extent threshold of at least 10 voxels, uncorrected voxel level at P<0.05. These results highlight different neural systems responding to unhealthy relative to healthy food under periods of restricted and habitual sleep. GFi, inferior frontal gyrus; GFm, medial frontal gyrus; GFs, superior frontal gyrus; GPoC, post central gyrus; GTm, middle temporal gyrus; GTs, superior frontal gyrus; PLi, inferior parietal lobe; TLm, medial temporal lobe. A full color version of this figure is available at the International Journal of Obesity online.

Figure 2

Right insular cortex, restricted>habitual sleep for unhealthy>healthy food. Relative change in the BOLD signal plotted against the relative change in caloric intake for each subject. For this correlation analysis, the region of interest (insula) was defined by an activation cluster derived from the group analysis (x, y, z: 40–47, −20 to −8, 10–20). Pearson's r= −0.280; n = 25.