Some of you may have seen or heard last month’s news reports stating that when we are sleep deprived, we crave junk food. These reports stemmed from a study conducted by Stephanie Greer and her colleagues at the University of California, Berkeley, which investigated changes in brain function after one night’s sleep deprivation, compared to a preceding night of healthy sleep. The researchers found that not only are the areas of our brain that make complex decisions impaired when we are sleep deprived, but there is more brain activity in the areas that control desire. When participants were shown a series of food images and asked to rate their desire for each item, they preferred high calorie foods, like burgers and pizzas.
Greer’s study adds to a growing body of work in this area and an increasing understanding of how short sleep might contribute to weight gain and obesity. We know that those of us who don’t get enough sleep have abnormal glucose metabolism, and abnormal hormonal control of appetite and satiety (feeling full). We tend to overeat when we are missing out on sleep. We crave high-calorie foods, we snack more often, our meal times become more irregular, and a higher proportion of our diet comes from fats and refined carbohydrates.
This week the link between junk food and sleep deprivation is back in the news. Colin Chapman at Uppsala University in Sweden studied the effect of sleep deprivation on our food purchasing choices. Participants were given a fixed budget and a representative selection of supermarket items, and asked to spend their entire budget on whatever foods they wanted. Following a night of sleep deprivation, they purchased more calories and greater portion sizes than when we they were well-rested.
Makes me wonder whether those days when my grocery bill is obscenely high, and I seem to have far too many packets of biscuits in the trolley, follow nights of bad sleep.