In a country as highly developed and comfortable as America, it’s almost shocking how widespread sleep deprivation is. According to the Centers for Disease Control and Prevention, more than a third of us are scraping by on less than seven hours per night. This is enough for them to describe sleep deprivation as an actual public health problem.
Calling sleepiness a public health problem might seem a little excessive. So what if some people would rather squeeze in an extra chapter of their book or watch another episode rather than turn in? Turns out, it’s a much bigger issue than it seems at first glance. One of the reasons sleep deprivation is such a problem is because it’s so easy to miss its symptom. And there are several really important ones that most people don’t link to their fatigue. For example…
1) Crummy Math Skills
In 1999, the journal Neuroreport published a study titled “Sleep deprivation-induced reduction in cortical functional response to serial subtraction.” The idea was to specifically measure the effect of sleeplessness on different areas of the brain, so the researchers had their subjects perform arithmetic problems inside an fMRI machine under two different sets of conditions. The first time, the subjects were well rested; the second was after a grueling thirty-five hours without sleep.
The results? The subjects were markedly worse at math when they weren’t rested. (Big surprise, right?) But what’s more, the study gave us a better reason than: “I don’t know, I’m tired!” The sleepy group had markedly less brain activity in their prefrontal cortex, which is responsible for planning, decision making, and moderating social behavior. Which also means…
2) A Bad Sense of Humor
It might seem hard to measure, but it takes a lot of finely tuned neurons to make you funny. Sleep deprivation significantly dulls a sharp brain, slowing cognition, hampering reaction time, and slaying social skills. That doesn’t just mean an objectively worse sense of humor—scientists actually measure it on what’s called the humor production sub-scale. It also means an impaired ability to empathize, read others’ emotions, make judgments, think about future consequences, and resolve conflict.
We don’t often think about it, but being the kind of person others want to be around requires a healthy brain that’s firing on all cylinders. When you’re sleepy, it’s not doing that, which is one reason why many studies have shown that an otherwise healthy relationship suffers badly when one partner is suffering from insomnia.
3) A Faulty Ticker
The odds of experiencing high blood pressure, irregular heartbeat, coronary artery disease, and heart attacks all increase with chronic sleep deprivation. In fact, seventy-five percent of people who have heart failure report frequent insomnia. Sure, people who are diagnosed with heart problems are more likely to experience depression and insomnia as a result of the diagnosis, but low sleep also has a causative effect.
Lack of sleep interferes with certain hormone levels, particularly ghrelin and leptin. These also control appetite, energy expenditure, and body fat, which increases the risk of metabolic syndrome, a group of risk factors that raises your risk for heart disease. Insomnia also tends to cause inflammation, which is linked to a host of chronic diseases, including atherosclerosis and heart attacks.
One of the more prominent studies on the subject, known as the Whitehall II Study, looked at more than 10,000 British civil servants over twenty years. Those who reduced their sleep from seven to five hours or fewer per night doubled their risk of death from cardiovascular disease.
What’t the lesson here? Get in bed and get some sleep!