Lack of Sleep and Obesity

Everyone knows that eating too much and being a couch potato are the main factors in becoming overweight or obese.  But a number of studies are pointing to lack of sleep as a contributing factor. An alarming 65 percent of Americans are now either overweight (BMI of 25-30) or obese (30 or more).

A Harvard study showed that people who sleep less than 6 hours a night have a higher BMI than average, whereas those who sleep eight or more hours have the lowest BMI.  This applies to adults and children.

 The Nurses Health Study followed 60,000 nurses for 16 years.  None were obese at the beginning.   They were asked about their diets, sleep habits, and weights as they went along.  Short sleepers (5 hours or less) had a 30 percent higher chance of putting on 30 pounds than those who slept 7 hours or more.

Forty percent of adults do not get the recommended amount of sleep, whereas, in the 1940s, only 11 percent came up short.  The Centers for Disease Control and Prevention (CDC) considers this a public health concern. It is interesting that the obesity epidemic in the US has also occurred in recent decades, and the numbers are still rising.

What actually happens in the body that causes weight gain from lack of sleep?  When asleep, the body produces hormones that help control hunger, regulate energy levels, and aid in glucose (blood sugar) processing.  Poor sleep disrupts the balance of these hormones, which are:

·       Cortisol, the “stress hormone,” is secreted when the body is not functioning smoothly due to lack of sleep.  It is also connected to insulin which regulates blood sugar and aids in fat storage.  Insulin is a factor in weight gain and diabetes.

·       Leptin is a hormone that signals the brain when a person has had enough food to eat, giving that full but not stuffed feeling. Lack of sleep can lower the level of leptin and cause the body to want more and more food.

·       Ghrelin is an appetite stimulant and higher levels, caused by poor sleep, can make a person hungrier.

When awake, the poor sleeper may not only be hungry but may want sweets for energy, develop food cravings, and a desire for comfort foods, which tend to be high in carbohydrates and fat.

Other reasons contributing to weight gain for poor sleepers are:

·       Being awake more hours means that a person is around food more, especially if awake at night.  A study of nurses that work the night shift as part of a rotation showed a greater chance of becoming obese and developing diabetes.

·       People who lack sufficient sleep are often too tired to exercise.  They don’t participate in sports or other activities and rest in front of the TV for much of their time.

Simply sleeping more is not a cure for obesity.  Too many other factors are in play. But enough sleep will elevate mood, improve concentration and alertness and raise the quality of life.