You can put gaining extra inches on your waistline to the list of health issues related to a lack of regular shut-eye – a list that already includes faster cell ageing, neuron damage, and reduced memory capability. That's the conclusion of new research that found adults sleeping for six hours a night had average waist measurements 3 centimetres (1.2 inches) larger than those sleeping for nine hours a night. What's going on? The team from the University of Leeds in the UK thinks a lack of sleep messes around with the chemical mix of our metabolism and our body's ability to maintain a healthy weight. "Our findings support the accumulating evidence showing an important contribution of short sleep to metabolic diseases such as obesity," report the researchers. Data was crunched from 1,615 UK adults, aged between 19 and 65, as part of the National Diet and Nutrition Survey Rolling Programme. Participants were asked to log sleep and food intake for four days, and weight, blood pressure, and waist circumference were also recorded. As well as the waistline difference, the shorter sleepers were heavier too: every extra hour of sleep between six and nine hours accounted for 0.46 kg/m2 lower BMI values in the adults surveyed. The data also showed a link between shorter sleep times and reduced levels of HDL cholesterol, the 'good' type of cholesterol responsible for removing harmful cholesterol from the bloodstream and reducing the risk of heart disease. However, this study didn't turn up any link between a less healthy diet and less sleep at night, a connection that has been made in the past. Overall it's more evidence for the positive benefits of banking seven, eight, or nine hours sleep instead of six a night – the researchers suggest the perfect amount is somewhere inside that range, depending on the person. The researchers also say their findings could provide new insight into the relationship between sleep and metabolic diseases like diabetes, which now affects more than 422 million people worldwide, according to the World Health Organisation. However the team stresses that this isn't a long-term look at chronic sleep problems and whether they lead to disease, but rather a snapshot of how sleep duration relates to these different measurements of metabolic health. The hope is if we understand more about the causes of obesity – such as reduced amounts of sleep in this case – then we're better able to tackle it and the related health issues. And while this study looked at a variety of metabolic measurements, it's far from the first study to conclude that poor sleep is at least one of the factors in our obesity problem. "The number of people with obesity worldwide has more than doubled since 1980," says one of the team, Greg Potter. "Obesity contributes to the development of many diseases, most notably type 2 diabetes." "Understanding why people gain weight has crucial implications for public health." The findings have been published in PLOS One. Source
