The relationship between sleep and metabolism is well researched. Studies have linked decreased sleep to greater calorie intake and increased abdominal fat. Not getting enough sleep affects appetite hormones, notably ghrelin and leptin, leading to increased hunger and food intake, decreased calorie burning and increased fat storage. A large study from Kaiser Permanente Center for Health Research, published in the ‘International Journal of Obesity’, found that dieters were most successful when they got just the right amount of sleep, which was six to eight hours a night. Another study, published in 2010 in the ‘Annals of Internal Medicine’, found that overweight people on calorie-restricted diets lost more body fat and retained more lean tissue (muscle) when they slept about eight hours instead of five hours a night.
A report from the Harvard School of Public Health says that there’s a link between how much people sleep and how much they weigh. In general, children and adults who get too little sleep, tend to weigh more than those who get enough sleep. There are, according to the report, several possible ways that sleep deprivation could increase the chances of becoming obese: Sleep-deprived people may be too tired to exercise, decreasing the ‘calories burnt’ side of the weight-change equation. Or people who don’t get enough sleep may take in more calories than those who do, simply because they are awake longer and have more opportunities to eat. Lack of sleep also disrupts the balance of key hormones that control appetite; so sleep-deprived people may be hungrier than those who get enough rest each night.
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Many people think that insomnia is usually a symptom of something else, like stress, a bad diet or a sedentary lifestyle, but this may not be true. It is possible that insomnia itself causes many of the conditions that it is seen as a symptom of. Using previous research that shows that insomnia causes a decrease in blood flow in the front dorsal lobe of the brain, and correlates it with depression, the authors of a Japanese study recently published in De Gruyter’s open access journal ‘Open Medicine’ sought to establish a link between insomnia and depression. They found that chronic insomnia can lead to depression, and a better understanding of the link between the two conditions could be used to improve treatment, and prevent the condition from worsening. The hope is a survey will be developed for healthcare professionals (and other high-stress professions) that can identify insomnia before it becomes a problem.