We all know that eating right and exercising are important to maintaining a healthy body weight. But years of research have also revealed a strong connection between inadequate sleep and being overweight—giving people yet another reason to make good quality sleep a priority.
Sleep and weight have been linked by scientists for a long time now. On average, the less people sleep, the more they weigh, and the more likely they are to put on excess pounds over time. For example, middle age adults who sleep fewer than seven hours per night have higher weights per height, and are more likely to be obese than those who sleep seven or more hours. One study of almost 70,000 women who were followed for 16 years found that those who slept five hours a night were 32 percent more likely to gain a lot of weight (33 pounds or more) than women who slept at least seven hours a night. Women who slept six hours per night were 12 percent more likely to gain at least 33 pounds over the course of the study.
Although the connection between sleep and weight is becoming clearer, the exact mechanisms involved are still being studied. Insufficient sleep is known to cause changes in hormones like ghrelin (which increases appetite) and leptin (which tells us we're full). The result is that sleepy people tend to feel hungry and consume more energy than those who are well rested. Indeed, imaging studies suggest that when people are sleep deprived, their brains respond differently to unhealthy foods, and they are less likely to resist eating them. Not sleeping enough is also known to lower a person's metabolic rate and affect the production of insulin.
Unfortunately, these changes extend to younger people as well. Lack of sleep has been shown to increase the risk of obesity in children. Given that childhood obesity rates have tripled in the last 30 years, doctors and researchers are starting to focus on the role of sleep in weight control. In combination with the effects on blood pressure and sugar, it's clear that sleep loss and excess body weight add a significant risk to health.