Adults are supposed to get between seven and nine hours of quality sleep each night, but the number of people getting by on six hours — or fewer — is on the rise.
With so many of us short-changing our sleep, it may not seem surprising that the number of Americans who rely on a daily jolt of coffee is also climbing. In fact, 63 percent of U.S. adults reported a daily java fix in 2019, according to a survey commissioned by the National Coffee Association USA (NCA).
If your days are hectic and you’re short on time, you might think sacrificing a few hours of shut-eye isn’t a big deal. After all, you can offset your resulting mental grogginess with a dose of caffeine.
Metabolic consequences of poor sleep
Inadequate sleep has been linked to overeating and trouble losing excess weight. Adults who sleep less than seven hours per night are more likely to report being obese than those who sleep seven or more hours, according to the Centers for Disease Control and Prevention.
You might assume this association is simply due to the fact that people who stay up late or don’t have a well-established sleep-wake routine are just too tired to be active or to work out. But the sleep-metabolism connection is more complicated than that.
Your circadian rhythms, or “body clock,” govern many biological systems, including appetite and metabolism. These internal clockworks are established mainly by genetics, but external factors, such as exercise, light exposure, meal times and sleep deprivation, can influence them.
In short, going to bed at different times and getting irregular amounts of sleep can have metabolic consequences. A May 2019 study involving 2,003 men and women between the ages of 45 and 84 years old found that inconsistent sleeping patterns are linked to a higher risk for obesity, high cholesterol, high blood pressure, high blood sugar and other metabolic problems. The findings, published in Diabetes Care, suggest that for every hour that bedtimes and sleep durations shift, people’s odds for a metabolic disorder may increase by up to 27 percent.
Sleep loss affects hormone levels
So, how does inconsistent, poor-quality sleep affect your metabolic health? Research suggests that sleep loss affects hormone levels tied to hunger, satiety, stress and even insulin sensitivity.
The cascade of metabolic changes that may result from poor sleep includes a drop in blood levels of leptin (a “satiety” hormone that triggers feelings of fullness after eating) and a rise in blood levels of ghrelin (a “hunger” hormone that stimulates appetite and helps regulate body weight over time).
As bedtime approaches, cortisol levels typically drop, but research shows that levels remain elevated in those who are sleep deprived. Over time, higher than normal cortisol levels due to poor sleep can lead to insulin resistance, increasing your risk for obesity and type 2 diabetes.
Moreover, if you’re routinely skimping on sleep, your levels of human growth hormone (HGH) may drop. In addition to your sleeping habits, the secretion of HGH is influenced by your age, gender, diet, level of physical activity and weight. It works in combination with another hormone, known as Insulin-like Growth Factor-1, to build muscle and burn body fat. Low levels of growth hormone are typically associated with obesity.
This content originally appeared on Sharecare.com.