The Sleep, Stress, Body Composition Equation
Sleep is the ultimate recovery tool, for both your brain and body. In fact, it’s one of the most important variables contributing to the success of any competitive athlete. But every woman—regardless of her athletic aspirations—needs a good night’s sleep in order to look and feel her very best.
While sleep is a complex and dynamic process that scientists still don’t fully understand, we know that every organ and system in the body benefits from it. Without enough sleep, the functions of our cognitive, immune, cardiovascular, respiratory, digestive, endocrine, and central nervous systems would all break down. And numerous research studies confirm that an inadequate amount of sleep (which can be defined differently for every woman) can have a negative effect on metabolism and body composition.
Women who skimp on sleep are more likely to accumulate excess body fat.
Why? During deep sleep, your brain secretes a large amount of growth hormone, which tells your body how to break down fat for fuel. When you’re low on sleep, you’re more likely to store calories as fat since there isn't enough growth hormone to break it down.
Sleep deprivation disrupts the production other important hormones, too. A lack of sleep will also decrease the production of ghrelin (the hunger-reducing hormone) and increase the production of leptin (the hunger-stimulating hormone). When you’re short on sleep, your body is programmed to tell your brain that it’s hungrier than usual. While sleep-deprived women don’t necessarily end up eating larger meals, they do consume more snacks (especially between the hours of 7:00 p.m. and 7:00 a.m.) which add an average of 220 additional calories to their diet each day.
And let’s be honest: when we’re hungry and tired, we’re much more likely to select foods based on their convenience.
Pre-packaged foods that are high in refined sugars and processed carbohydrates—cookies, crackers, and chips; breads, pastas, and cereals—become a quick fix. And research studies confirm that sleep-deprived women consistently crave these same sweet and/or starchy foods. As it turns out, sugar and carbohydrate cravings are an unbalanced body’s way of asking for easy energy. Chronically sleep deprived woman who become dependent on these nutrient-poor foods as a primary source of fuel will be much more likely to develop a metabolic disorder.
If hormone dysregulation, increased hunger, and food cravings weren’t already enough, sleep deprivation makes it easier for women to pack on pounds by reducing their basal metabolic rate or BMR—the minimum number of calories needed to support the body’s basic, physiological functions while at rest.
In fact, sleeping less can lower your BMR by as much as 20%, significantly reducing your total energy output.
Your basal metabolic rate is regulated by your thyroid gland, which produces the T3 and T4 hormones, under the direction of thyroid stimulating hormone or TSH (produced by the pituitary gland). TSH stimulates the production of thyroid hormones and these hormones, in turn, boost metabolic rate. One study showed that after 6 days of sleeping only 4 hours a night, women’s TSH levels fell by an average of 30%. Fortunately, this drop is reversible. Once the subjects returned to their regular sleeping routine, their TSH returned to normal.
Stress is yet another reason why sleep-deprived women find themselves struggling with poor body composition and weight loss resistance.
Any type of stress can cause dramatic changes in the female body and inadequate sleep is a form of stress. Cortisol is a hormone helps the body adapt to its harmful effects. Since it’s a catabolic hormone, however, cortisol can do more harm than good. It breaks down tissues—including muscles—in order to provide the body with the energy it needs to re-establish its internal homeostasis. Research has shown that a just single night of sleep deprivation can increase the body’s cortisol level by as much as 45%. Since cortisol suppresses immune function, you’ll be more prone to catching a cold or flu when you don’t sleep enough.
The sympathetic or “fight of flight” nervous system is also activated when the body is under stress. When the sympathetic nervous system is in charge, blood is diverted away from less-essential organs—including the intestines—creating biochemical changes that encourage stubborn weight loss and the accumulation of excess belly fat.
According to Dr. Sanjay Patel, at least two dozen studies have confirmed that women weigh more if they sleep less.
In a 16-year study of almost 70,000 women, Dr. Patel and his colleagues found that those who slept five hours or less a night were 30% more likely to gain 30 or more pounds than those who got more rest. Some experts believe that a lack of sleep is one reason for America's obesity epidemic. According to the National Sleep Foundation, the average American woman gets six hours and 40 minutes of sleep most nights—far less than the eight-hour minimum most experts recommend.
If sleeping less causes weight gain, can sleeping more lead to weight loss?
In 2009, sleep and medical experts Michael Brues, PhD and Steven Lamm, MD created a weight loss plan for seven Glamour magazine readers that involved just one thing: sleeping more for four weeks. Without making any other changes in their diet or activity level, all seven women lost between six and 12 pounds of weight.
If your health and fitness goals include fat loss for improved body composition, sleeping more might just be the most beneficial thing you can do.
Now that you’ve done a little bit of reading on the topic, what do you think? Is sleeping your way to a better body composition something you’re willing to try? Please share your thoughts in the comments section below.