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

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

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.

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

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.

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.

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.