Walking around at work in the morning, something you’re probably not going to hear from colleagues is: “I feel so well rested; every night I get so much sleep!” Instead, you are much more likely to hear complaints about how exhausted everyone feels, how late they stayed up the previous night, and how they hit snooze four times when their alarm went off because they were so tired. Lack of sleep is such a common problem, with more than 33 percent of Americans admitting to getting fewer than seven hours per night according to the Centers for Disease Control and Prevention. So it’s particularly bad news that new research suggests getting too little sleep is also associated with gaining unhealthy weight.
The study, which took place at the University of Leeds in in the United Kingdom, found that people who lack sufficient nightly sleep have a greater likelihood of being overweight and having a bigger waist.1 Potter, Gregory D.M.; et al. “Longer sleep is associated with lower BMI and favorable metabolic profiles in UK adults: Findings from the National Diet and Nutrition Survey.” PLoS One. 27 July 2017. Accessed 6 August 2017. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182195. To develop a clearer picture of the effects of sleep on various aspects of health, the investigators recruited 1,615 men and women living in the U.K. They answered questionnaires focused on their typical dietary habits and sleeping patterns. In addition, the subjects underwent a physical exam that included drawing blood, taking measurements of their weight and waist circumference, and testing blood pressure, blood sugar levels, cholesterol levels, and thyroid function.
The results showed that insufficient sleep was correlated with poorer health in several ways. Participants who typically got 5.9 hours of sleep nightly averaged a body-mass index (BMI) of 28.6 and a waist circumference of 37.4 inches. In contrast, those who typically slept for 8.4 hours nightly had an average BMI of 27.1 and waist circumference of 35.8 inches. In addition, the findings showed that less than optimal sleep per night was associated with higher blood sugar levels, increased inflammation, and decreased thyroid function. However, none of these were found to be statistically significant.
Nevertheless, these assessments are important indicators of whether or not a person is at a healthy weight. BMI is an overall gauge of body fat based on a weight-to-height ratio, with normal weight BMI ranging from 18.5 to 24.9, and overweight represented by 25 or higher. It should be noted, then, that even the volunteers getting more than eight hours of sleep on average were overweight, but not by nearly as much as their peers sleeping less. Waist circumference measures the extent of dangerous abdominal fat, which was linked in a 2014 study at the Mayo Clinic in Rochester, Minnesota to higher rates of heart disease, respiratory illnesses, cancer, and premature death.2 Cerhan, James R.; et al. “A Pooled Analysis of Waist Circumference and Mortality in 650,000 Adults.” Mayo Clinic Proceedings. March 2014. Accessed 7 August 2017. http://www.mayoclinicproceedings.org/article/S0025-6196(13)01040-9/fulltext.
When the researchers controlled for factors such as gender, age, income levels, ethnic background, and smoking, the outcomes were the same. In fact, every additional hour of nightly sleep a subject got was linked to a almost one-third of an inch decrease in waist circumference and a drop in BMI of close to half a point. (Then again, it should be noted that too much sleep may not be associated with weight gain, but it is associated with a lowered life expectancy and depression. But how often do you hear people complaining about getting too much sleep. In any case, for most people, the sweet spot appears to be between seven and eight hours a night.)
Surprisingly, the data did not determine a connection between the average length of sleep and dietary quality. This is the opposite of earlier findings, including a 2013 study at the University of California, Berkeley that showed poor dietary choices are frequently made by those getting too little sleep.3 Greer, Stephanie M.; et al. “The impact of sleep deprivation on food desire in the human brain.” Nature Communications. 6 August 2013. Accessed 7 August 2017. http://www.nature.com/articles/ncomms3259. And it begs the question of why these individuals would be heavier and carrying more weight in their midsection if they are not eating less nutritiously.
It’s certainly possible that the survey’s answers regarding foods consumed were not totally accurate, either due to misremembering or simply embarrassment at some of the unhealthy foods the participants had eaten. But it is also likely that it’s not only our willpower to stick to healthier eating that may be affected when we are chronically getting too little sleep.
Insufficient sleep has been linked to diabetes, cardiovascular disease, and early death, demonstrating that it has a negative effect on health independent of other factors. So, in addition to putting us at elevated risk for conditions related to overweight and obesity, that also means that if we are short on sleep, we might face a greater chance of developing these problems even if we are thinner.
The National Sleep Foundation recommends seven to nine hours a night as the appropriate amount of sleep for adults, but that ignores the studies that indicate that anything over eight hours may be problematic. That said, it’s important to make getting enough sleep your goal and really try to achieve it most of the time. It may require shooting for an earlier bedtime, starting a relaxation routine at night, and putting away your cell phone and other blue-light devices at least an hour before slumber, but it’s worth it for your health.
|↑1||Potter, Gregory D.M.; et al. “Longer sleep is associated with lower BMI and favorable metabolic profiles in UK adults: Findings from the National Diet and Nutrition Survey.” PLoS One. 27 July 2017. Accessed 6 August 2017. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182195.|
|↑2||Cerhan, James R.; et al. “A Pooled Analysis of Waist Circumference and Mortality in 650,000 Adults.” Mayo Clinic Proceedings. March 2014. Accessed 7 August 2017. http://www.mayoclinicproceedings.org/article/S0025-6196(13)01040-9/fulltext.|
|↑3||Greer, Stephanie M.; et al. “The impact of sleep deprivation on food desire in the human brain.” Nature Communications. 6 August 2013. Accessed 7 August 2017. http://www.nature.com/articles/ncomms3259.|