It may seem obvious to most that sleep is beneficial. Even without fully understanding what sleep does for us, we know that going without sleep for too long can make us feel terrible. While we may not often think about why we sleep, most of us acknowledge at some level that sleep does in fact make us feel better. With the proper amount of sleep, we feel more alert, more energetic, happier, and are better able to function through our daily routines. However, the fact that sleep makes us feel better and that going without sleep makes us feel worse only begins to explain why sleep is essential.
Scientists have spent many hours attempting to fully understand sleep’s benefits. In studies of humans and animals, they have discovered that sleep plays a critical role in immune function, metabolism, memory, learning, and other vital physical functions. Further, our bodies regulate sleep in much the same way that they regulate eating, drinking, and breathing suggesting that sleep serves a similar critical role in our health and overall well-being.
In the short term, a lack of adequate sleep can affect judgment, mood, ability to learn and retain information, and may increase the risk of serious accidents and injury. In the long term, chronic sleep deprivation may lead to many serious health problems including obesity, diabetes, cardiovascular disease, and even early mortality.
Related to obesity, there have been several studies that have demonstrated a significant link between insufficient sleep and weight gain. For example, studies have shown that people who habitually sleep less than six hours per night are much more likely to have a higher than average Body Mass Index (BMI) and that people who sleep eight hours or more have the lowest BMI. The results have led sleep to be seen as another potential risk factor for obesity along with the two most commonly identified risk factors: lack of exercise and overeating.
Research into the mechanisms involved in regulating metabolism and appetite are beginning to explain what the connection between sleep and obesity might be. During sleep, our bodies secrete hormones that help to control appetite, energy metabolism, and glucose processing. Obtaining too little sleep upsets the balance of these and other hormones such hormone as cortisol, often referred to as the “stress hormone”. Further, poor sleep is also associated with increases in the secretion of insulin, which is a hormone that regulates glucose processing and promotes fat storage creating a higher risk for diabetes.
Insufficient sleep has also been associated with lower levels of leptin, a hormone that alerts the brain that it has enough food, as well as higher levels of ghrelin a biochemical that stimulates appetite. As a result, poor sleep may result in food cravings even after an adequate number of calories have been consumed.
The cost of inadequate or insufficient sleep is much greater than many people think: it may have profound consequences for our long-term health. Treating sleep as a priority, rather than a luxury, may be an important step in preventing a number of chronic medical conditions leading to a long and healthy life.