Up all night. Can't Sleep. Obsessively checking Facebook at 4:00 a.m.

You've done it. Maybe even last night. More than 60 million Americans suffer from insomnia at some point in their lives, making it such a major issue that the Centers for Disease Control and Prevention recently called insufficient sleep a "public health problem."

But is there something else going on when you keep staring at the clock? Is insomnia more of a mental game than a physical one? Is it both? In honor of Mental Health Awareness Week (which runs from Oct. 4 through 10), MTV News spoke to a sleep expert about the causes and effects of insomnia.

Insomnia Is Super Common, But Still Misunderstood

According to the CDC, sleeplessness has been blamed for car crashes, industrial disasters and linked to hypertension, diabetes, depression, obesity and even some forms of cancer.

What's harder to discern for most people, though, is whether insomnia itself is a mental health or physical health issue.

"It's probably not useful to make that distinction," Dr. David Neubauer of the Johns Hopkins Sleep Disorders Center told MTV News. "When you look at some fundamental mental disorders you will find sleep disturbance there. Some of the criteria leading to major depression include insomnia." The same goes for everything from anxiety disorders to PTSD and bi-polar disorder. All have a disturbance of sleep as a common factor.

"Think of it as a two-way street," Neubauer said. "When people with mental illnesses are experiencing a depressive, manic episode or increased anxiety they very commonly have problems with sleep associated with those episodes."

From one point of view, he said, those mental illnesses can lead to sleep disturbances, but on the other, people who have a consistent sleep issue that goes on for months or years have a greater risk of developing a diagnosable mental disorder than those who don't have insomnia.

Why Don't Teens Sleep?

There are a variety of reasons why so many teenagers struggle to sleep — from overbooked schedules and busy social lives, to hormones, to just plain wrong attitudes about the importance of sleep, according to a UCLA Sleep Center study.

"Lots of people don't get the sleep they need to function adequately," Neubauer said. "But part of the challenge with teens and young adults is that they have so much going on that many don't prioritize sleep or recognize how important it is for their physical, mental, intellectual and cognitive functioning."

You don't just want to stay up later because you have so much to do or the freedom of being a bit older allows you to push boundaries, though. Because of the hormonal changes that occur during adolescence and delays in circadian rhythms (your body's internal clock), "it's perfectly natural for sleepiness at bed time to come on later and extend later into the following morning,” Neubauer said.

When you are sleep deprived, your brain and body don't function correctly. Neubauer said teens who don't get enough rest are more likely to have accidents and take other risks, may become more emotional or impulsive and can possibly develop eating disorders — which can morph into other chronic physical issues like diabetes and obesity.

This Is Why Your Body Won't Listen To Your Brain

If you can't fall asleep until 1:00 a.m., good luck getting enough rest if you have to be in class by 7:30 the next morning. And "if you're not getting enough sleep until the middle of the night, then you're not functioning well during the daytime," Neubauer said. "You would think that because you didn't get enough sleep the night before you'd got to sleep earlier the next night, but your biological clock doesn't work that way."

In fact, the majority of high school and college students are most biologically awake during the evening, which makes it a challenge to fall asleep as early as they might like. One thing that makes it even harder? Screens. "If you have a screen close to your eyes playing games or watching shows or being on Facebook that can be socially and biologically stimulating," Neubauer said. "Light exposure can further keep people awake and delay rhythms so you're alert too late into the night."

Are We Taking Insomnia Seriously Enough?

While there are lots of over-the-counter and prescription insomnia medications, and plenty of advice on strategies ranging from limiting naps to getting more exercise, reducing stress and cutting out non-sleep activities like watching TV in your bed, the bigger question is: Is modern medicine taking this issue seriously enough?

"Right now we've made a lot of progress on this," Neubauer said. "Medicine has a great appreciation of sleep disorders and the problem of inadequate sleep. But sometimes insomnia is not taken very seriously." That might be because health care providers are often undermined by the increasingly limited amount of time they have with patients and a focus on larger, more life-threatening health issues.

"Also, some individuals don't think of it as a health problem," he said. "It may not be obvious during your teen years, but if you chronically sleep less you are more likely to have all sorts of health problems later. That's why it's important to make sleep a priority and if you have a sleep disorder to get it evaluated."