If you're ever tempted to cut back on sleep in order to cross one more item off your to-do list, or cram for an exam, or read just one more chapter, you might resent how much time you "waste" sleeping.

Sleep researchers say it's unlikely humans could ever get by without sleep, but progress has been made toward optimizing sleep into condensed periods. And, while it may seem like a waste of time, sleep is essential for a vast list of body and brain functions, neuro-imaging technology has shown.

Much of the research being done is borne out of necessity: Soldiers, for example, can't always rely on an 8-hour window to sleep, but they must be able to perform at an optimal level at a moment's notice. Regular sleep is still by far the optimal method of recharging.

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The drawbacks of traditional methods of staying awake -- caffeine and pharmaceuticals -- make them less than ideal for long-term use.

"If you use a sleep pill you have to devote sufficient downtime" to allow the compound to clear from the body, said Dr. Nancy Wesensten of the Walter Reed Army Institute of Research, who studies sleep in order to help soldiers optimize their rest.

"Under field conditions, that might pose a problem if an emergency arises and you have to perform," Wesensten said. "What we're looking into are non-pharmacological ways to get more bang for your buck out of the sleep opportunities you have."

Wesensten says there are ways to drive recuperation during sleep using electrical stimulation, and possibly improve memory.

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"There's some evidence it can be done," she said, "and some investigators have shown the procedure increases the positive impact of sleep on memory. First you can see whether you can produce a signal in the brain during sleep, and then transition someone into a deeper stage of sleep more rapidly."

That transition period is key, agrees Chris Berka, CEO and co-founder of Advanced Brain Monitoring.

"Usually we waste the most time trying to fall asleep," she said. "In some cases it can take 30 minutes."

Advanced Brain Monitoring is working on a mask, for example, that incorporates EEG-based data to provide facial warmth that can accelerate sleep and promote deeper sleep, and luminescent blue lights to invoke lighter stages of sleep to ease the wakeup process -- or to make the most out of a short nap.

"If you only have 30 minutes to nap, you want to get into stage 2 and stay there," Berka said.

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If you're hoping to get by with less sleep, though, the best way to accomplish it is probably by being lucky. Recent research points to the probability that some people are "short-sleepers."

"As many as 15 percent of the population may survive and thrive on less sleep, like four to five hours a night," Berka said.

And many of us might not have any desire to cut back. "When you close your eyes but you’re still awake, the hypnagogic stage, is a period of time when a lot of people have creative insights and visions, so often they want to prolong that state," Berka said.

In fact, when psychiatrist Thomas Wehr of the National Institute of Mental Health gave participants in a research study 14 hours of rest time a night, after a few weeks they reported a kind of clarity they described as a crystal clear consciousness, begging the question: Do we know what it's like to be awake?