Sleep Loss Leads to Junk Food Cravings, Obesity: Study

Scientists have found proof that the lack of sleep can cause changes in brain activity to lead people into thinking they feel hungry and crave junk food.

For years, researchers have identified a correlation between the sharp rise of obesity in developed nations and a decline in sleeping times. Although a causal link was suspected, scientists have not yet explained the mechanism until this study came out.

Researchers from the University of California used magnetic resonance imaging (MRI) scans to identify changes in brain activity of people who lacked sleep.

The study, published in Nature Communications journal, said the findings suggest an explanatory brain mechanism in which lack of sleep can cause obesity. Sleep deprivation can lead people to overeat and crave fattening food. If sleeping patterns are not corrected, the sleep-deprived will eat his or her way to obesity.

Twenty-three test subjects had their brains scanned twice. One brain scan was taken after a full night's sleep and another scan after being deprived of sleep for one night. Researchers measured their brain activity as they chose food and portion sizes from a collection of 80 photos of different food types.

Among the sleep-deprived subjects, researchers have observed impaired activity in the areas of the brain's cortex that evaluate appetite and satiation. They also found increased brain activity in relation to food cravings.

Matthew Walker, co-author of the study from the psychology department of Berkeley's University of California, said the findings related to impaired brain activity in regions controlling judgment and logic along with regions of the brain linked to rewards help explain the link between sleep deprivation, obesity and weight gain.

The researchers recommend getting enough sleep to prevent excessive weight gain or obesity and make more appropriate food choices.

More than 1.4 billion adults starting at 20 years of age and up were overweight in 2008, according to data from the World Health Organisation. The number of adults in Australia who are obese or overweight has also increased the past few years along with the risk of heart disease and diabetes.