Scientists have suspected that there is a strong correlation between sleep deprivation and weight gain, as indicated by various studies over the years. For instance, one study reported that people who slept less than 6 hours a night had their body mass index (BMI) increased more than those who slept 7 to 8 hours. In another 16-year study, women slept 5 hours or less gained more weight than those who slept 7 hours a day. Nevertheless, the actual reasons behind these had yet to be unveiled.
BMI is a simple and common indicator to determine whether a person is overweight, obese or of normal weight. It is calculated by dividing the weight in kilos by the square of height in meters.
On August 6, 2013, researchers from the University of California in Berkeley reported in journal ‘Nature Communications’ that they had found a brain mechanism that could explain how sleep deprivation might lead to the development and maintenance of obesity.
In the study, researchers used magnetic resonance imaging (MRI) scans to spot changes in the brain activity of 23 participants. These participants had their head scanned twice: once after a full night of sleep and once after being deprived their shut-eye for a night. Their brain activity measured the next day as they selected items and portion sizes from pictures of 80 different food types.
Impaired activity in regions of the cortex that evaluate appetite and satiation was found among the sleep-deprived participants. Simultaneously, there was a boost in areas associated with craving. The study also found that high calorie foods became more desirable to the sleep deprived participants.
According to researchers, the link between sleep loss, weight gain and obesity can be explained by the impaired brain activity found in regions that control good judgment and decision making coupled with amplified activity in more reward-related brain regions.
They also believed that having enough amounts of sleep regularly might be a good way to promote weight control, which is achieved by priming the brain mechanisms governing appropriate food choices.