Tired? Much of the nation is, too, and lack of sleep could mean more than just red eyes or grogginess.
50 to 70 million Americans have some type of sleep disorder or chronic under-sleeping that impairs their day-to-day performance.
The typical person needs between eight and eight-and-a-half hours of sleep per night. But Americans now get an average of six-and-a-half hours on weekdays, and the amount of time spent in the sack is on the decline.
"Americans with each passing decade are getting more and more sleep deprived," said Dr. Charles Czeisler of the Brigham and Women's Hospital in Boston, who studies the effects of insufficient sleep on people's lives.
For people who suffer lack of sleep, there's no quick fix. A common misperception, he said, is that someone can make up for lost sleep in one night.
"A lot of people think, 'Well, I haven't gotten enough sleep for the past month, and I'm just going to spend 10 hours in bed tonight … and then I'll definitely be at my best tomorrow,' " Czeisler said. "It's going take them weeks to recover."
Experts say people who cut back on sleep by even a few hours each night will, within a week, be just as impaired as if they had pulled an all-nighter.
"In fact, companies, when they have employees who are sleep deprived, experience what you might call 'presenteeism' -- where they're at work, physically present, but they're not working at nearly their full potential," Czeisler said.
Risks to Health and Safety
Not only does sleep deprivation have dire health consequences, it makes people more likely to mess up.
Czeisler has found that when medical residents work long, 30-hour shifts, they are seven times more likely to make serious mistakes. That's because when the brain is deprived of sleep, it begins to short circuit, particularly in the pre-frontal cortex responsible for judgment and decision making.
When the pressure for sleep reaches a critical point, a "sleep switch" in the hypothalamus flips, sending a person into a state of sleep -- even if they're chugging caffeine or driving a car. An estimated 80,000 Americans fall asleep at the wheel every day, resulting in about 8,000 deaths a year.
As America's sleep deficit grows, so does its waistline.
"When we get an inadequate amount of sleep at night, there are changes in our body's metabolism that almost mimic starvation," Czeisler said. "So, we have carbohydrate cravings and we eat more."
For those trying to shed pounds, one of the most powerful tools may be a pillow.
As for how and when to sleep, experts say it's not a good thing to fall asleep at the drop of a hat. That means the body is exhausted and is plunging itself into sleep the minute it has the chance. Normally, the body should take about 15 to 20 minutes to fall asleep.
Naps, on the other hand, can help jump-start the body.
NASA did a study on naps and found that a short, 26-minute nap boosted performance by 34 percent and alertness by 54 percent. But while power naps help, they won't make up for a big sleep deficit. When nighttime comes, nothing beats a full eight hours of rest.