MedWire News: Acute sleep deprivation stimulates areas of the brain involved in triggering the hunger response and may therefore increase a person's risk for becoming obese, say researchers.
"These findings highlight a potentially important mechanism contributing to the growing levels of obesity in Western society," write Christian Benedict (Uppsala University, Sweden) and colleagues in the Journal of Clinical Endocrinology and Metabolism.
Previous research showed that a single night of sleep loss in young healthy men can reduce energy expenditure the next day and that the same individuals had increased levels of hunger.
To investigate this further, Benedict and co-workers recruited 12 normal-weight men aged 23.3 years on average to take part in a sleep deprivation study to assess which areas of the brain are activated as a result of sleep loss.
The researchers measured neural activation in response to food triggers by functional magnetic resonance imaging (fMRI) after the men had undergone one night of normal sleep and after one night of total sleep deprivation.
The food triggers involved a selection of images of high- and low-calorie foods that were presented at random to the men who were asked to rate them as appetizing or nonappetizing. Hunger and appetite ratings were also taken after a night of sleep and of sleep deprivation.
The team reports that increased activation of the right anterior cingulate cortex, an area involved in hunger control, was observed in the participants in response to viewing food images after sleep deprivation, but not after sleep. This finding was independent of prescan hunger ratings and calorie content of the individual food types.
Of note, the increased activation in this area of the brain in sleep-deprived individuals was positively correlated with their postscan appetite ratings.
The men reported increased hunger after sleep deprivation compared with normal sleep, but no changes in fasting plasma glucose were observed.
Benedict and team say "our findings show that the neural response to rewarding food cues is sensitive to the disruption of the sleep-wake cycle, as frequently occurs, for example, in shift workers."
Commenting in a press statement, Benedict said: "After a night of total sleep loss, these males showed a high level of activation in an area of the brain that is involved in a desire to eat. Bearing in mind that insufficient sleep is a growing problem in modern society, our results may explain why poor sleep habits can affect people's risk to gain weight in the long run. It may therefore be important to sleep about eight hours every night to maintain a stable and healthy body weight."
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