Life in a 24-7 world leaves many of us  joking, "I'll sleep when I'm dead." But it's a deadly serious fact that sleep deprivation can kill you. According to the National Geographic special "Sleepless in America," 40 percent of American adults and 70 percent of adolescents are sleep-deprived, which has major health and safety consequences.

Waking earlier, going to bed later, and sleeping less than seven to eight hours not only affects our ability to function, but leaves us prone to obesity, diabetes, hypertension, heart disease, stroke, Alzheimer's disease, anxiety, depression and cancer.

Explaining the science and implications of insomnia, the documentary — which airs on Nov. 30 — includes sobering statistics and research such as the study by Dr. David Gozal of the University of Chicago indicating poor sleep may double the speed of cancer growth. Drowsy driving also causes an estimated 1,000 fatal car crashes per year and diminished productivity due to lack of sleep costs American business $100 billion annually. The 15 million people who work the night shift and those who suffer from sleep apnea especially are at an increased risk for various health issues. It's enough to keep you up all night — if you aren't already. 

Cognitive impairment is another consequence. "If you look at modern‑day society in industrialized nations, technology invasion into the bedroom at night, and longer commute times in the morning, the thing that people shortchange most in modern‑day life is sleep. And the elastic band can stretch only so far before it snaps," says Matthew Walker, PhD, director of the Sleep and Neuroimaging Laboratory at the University of California, Berkeley. "Human beings are the only species that will deliberately deprive themselves of sleep," he points out, to the detriment of their brains. "Sleep is important for learning and memory, and is not like the bank. You can't accumulate a debt and then hope to pay it off at a later point in time. If you don't snooze, you lose."

In the documentary, Dr. Eve Van Cauter, professor of medicine and director of the Sleep, Metabolism, and Health Center at the University of Chicago, presents a study in which subjects who had four hours' sleep for just two nights had the metabolic profile of Type 2 diabetic.

In the video below, teens and experts discuss the sleeping habits of American youths.

She points out that sleep deprivation will also seriously aggravate any pre-existing medical condition. "Your cancer will spread more quickly if you don't sleep well or enough. Your diabetes will be more severe. If you have obstructive sleep apnea at the same time, it's really rollerblading uphill. If you want to lose weight, to do so while not sleeping enough is really counterproductive, because we are wired to associate waking and eating. The more you are awake, the more your brain tells you to eat — we sleep‑deprive ourselves, and we forage the refrigerator. If you want to lose weight, you need your sleep."

Dr. Mark Rosekind, a fatigue expert who serves on the National Transportation Safety Board, investigating major transportation accidents, has seen the lethal consequences of sleep deprivation first hand. "At the NTSB we determine the probable cause of accidents and issue recommendations so they don't happen again. Fatigue and sleep loss have been on our radar for a long time. Over a 10-year period, 2001 to 2012, 20 percent of all the fatal accidents we investigated had a fatigue element; highway it was 40 percent," he says. "Your decision-making, your ability to pay attention, your communication skills, learning, memory, all those things are going to be degraded. Everybody cheats on sleep so they can fit more stuff in, but it has the opposite result."

Rosekind says the fact that "we're never disconnected" is to blame for a lot of sleep problems. "A study showed that kids who have any kind of technology in their bedrooms — gaming console, tablet etc. — average one hour less sleep than those who don't. This doesn't mean you can't be connected and use your technology, just don't bring it in the bedroom." It's one of several practical suggestions he has for improving sleep.

"One thing that's critical is giving yourself enough time for sleep, at least eight hours," he begins. "Go to bed at a regular time and wake up at a regular time. The wake time is more critical than the bedtime because our internal clock knows what time it is from light. If you're going to cheat, stay up later but keep the wake time as close to your regular time as possible."

Next, "Develop a pre-bedtime routine so you teach your body to relax and go to sleep. Get in your jammies, brush your teeth, read a book, whatever your cues are to get you ready for sleep. You can take these with you on the road when you're traveling,” he notes. Keep the room "cool, dark and quiet. 67-68 degrees is the perfect sleeping temperature for most people," Rosekind says, adding that light sleepers can benefit from earplugs or noise machines.

"The number one cause of insomnia is worrying about something," he points out, proposing a few solutions. Write down your concerns and what you're going to do about them an hour or two before heading to your bedroom. Do yoga or stretching to relax your muscles. Give yourself something to focus on, like counting sheep, or read something boring, "like government report."

Rosekind hopes that viewers will take these suggestions and the warnings in "Sleepless in America" to heart. "This is a topic that affects everybody," he says. "The important thing is that people not only learn but change their behavior."

Related on MNN: