Fort Detrick Standard, March 2003

Karen Fleming-Michael

O sleep! O gentle sleep! Nature's soft nurse, how have I frighted thee, That thou no more wilt weigh my eyelids down And steep my senses in forgetfulness?
--William Shakespeare Henry IV

Though military operations take place at all hours and for long hours, there's no getting around it: warfighters need their sleep.

"There's nothing heroic about staying up," said Col. Gregory Belenky, lead sleep researcher at the Walter Reed Army Institute of Research. In fact, he said warfighters who deprive themselves of sleep can cause missions to fail.

"Historically, battles are won and lost at the small unit level, squads and platoons, and because of the interaction between individuals within squads and between squads," said Belenky, a psychiatrist who has studied sleep for the Army since 1984. "If you're sleep deprived, you're not going to make good decisions."

Sleep deprived battle planners, too, can make poor decisions, said Lt. Col. Robert Noback, who studies aircrew health and performance at the U.S. Army Aeromedical Research Lab at Fort Rucker, Ala. "The battle staff frequently gets less sleep than the soldiers on point, so they are just as much at risk of making bad decisions...and if they are, the tired soldiers on point will make bad decisions based on bad plans from tired planners."

The military studies sleep in two types of operations, sustained and continuous. During sustained operations, warfighters get less than four hours sleep each night, which is considered severe sleep restriction or deprivation. Conversely, sustained operations can go on for days. During continuous operations, warfighters get four or more but less than seven hours sleep each night, which is considered mild to moderate sleep restriction.

Continuous operations can go on for weeks or months, and typical of most U.S. Army operational deployments, continuous operations can be punctuated by periods of sustained operations.

Both sustained and continuous operations take their toll, but it appears that warfighters recover faster from sustained operations than continuous ones, Belenky said. "Recovery from continuous operations is not rapid," he said. "What complicates deprivation is that sustained operations can be interposed on continuous operations, so already-sleep-deprived soldiers are getting even more off track with their sleep."

Going off sleep's beaten path can have serious consequences for warfighters trying to make decisions, process information and judge situations because the regions of the brain best able to perform these actions are most affected by lack of sleep. Degraded activity in what Belenky calls "objective force brain areas"--the brain's front (prefrontal cortex), sides (parietal cortex) and thalamus--can pose great peril to future combat units.

"Everything you hear about the objective force--the devolution of command and control down to low levels, huge decisions being made by small groups of people with no redundancy and no back up--there are going to be a lot of autonomous agents interacting with other autonomous agents, and that requires a lot of processing power on the part of the individual," he said.

Warfighters, he said, will encounter a lot of information and need to be able to process it at their level to make decisions. "You can have a brilliant plan, but unless you have intelligent execution at the lowest level, it won't work," Belenky said. Sleep-deprived warfighters, he said, because their higher order thinking is impaired, can cause accidents and "not so clever decisions."

To quell some of the effects of sleep deprivation during operations, a team of 15 researchers, including physicians, physiologists and experimental psychologists, study sleep at WRAIR for the Department of Defense. Findings are included in peer-reviewed literature like the Journal of Sleep Research as well as Army field manuals, like U.S. Army Field Manual 6-22.5 "Combat Stress" and FM 22-51 "Leader's Manual for Combat Stress Control."

Because restricted sleep is a reality for warfighters, researchers base their lab studies on that condition. For example, in experiments done at WRAIR's sleep lab, it was evident that people who lived on three, five and seven hours of sleep for more than a week took longer than three days to recover.

"We don't know how long it takes them to recover," Belenky said. "The brain adapts, and like adaptations to exercise, starvation and altitude, they take a while to put in place and for a price they improve performance in that particular context and they also take a while to undo."

To help commanders in the field determine the toll that less sleep takes on troops, WRAIR researchers developed a sleep watch that measures arm movement to determine if someone is awake or asleep and records how much sleep he or she got. The sleep watch also has a performance prediction model that tells how well the individual is performing and will perform in the future.

When researchers developed the watch, they took a logistician's approach of treating sleep as a consumable that can be restocked. "You wouldn't ask a battalion commander to manage fuel ... unless the commander knew how much he had on hand, what his fuel use would be in an operation and what would be available for resupply," Belenky said. "The sleep watch gives the commander what he needs to look at for how much sleep his troops have been getting and what the performance consequences are with that amount of sleep." The commander, then, can look at factors, like fuel, ammunition, food and sleep, to make an educated decision about whether the unit is ready for a mission.

Because people's need for sleep varies as much as their personalities, Army researchers are exploring ways to alter the watch's current one-size-fits-all presentation. Current design plans include a test that warfighters can take a few times a day for several weeks that can help predict how they will perform. The sleep watch will be included in the Objective Force Warrior's Scorpion ensemble as part of the Warfighter Physiological Status Monitoring System being developed by the U.S. Army Research Institute of Environmental Medicine in Natick, Mass. The system will provide commanders and medics aggregate information on troops' physical readiness, such as thermal stress, hydration status and cognitive state.

Army researchers have also looked at stimulants to see if they are effective in keeping soldiers awake and able to make sound decisions.

"Stimulants have their place and are very effective ... but there's no standard right now for who should take a stimulant," Belenky said. He added that he would like to see stimulant use and dose targeted toward individuals, not populations, so a person gets just what they need to perform, no more and no less.

When looking at different stimulants, it's no surprise studies have shown the long-time friend of the soldier, caffeine, is an effective aid, Noback said. For caffeine to be most effective, Belenky said regular users need to minimize their caffeine use so when they need it, caffeine will give them a boost. In upcoming studies, WRAIR researchers will test caffeine, d-amphetamine and modafinil to see which of those three stimulants produces the best results.

The bottom line with stimulants, Belenky said, is they are "short-term fixes at best. The real answer is to get adequate amounts of sleep and efficiently managed sleep."

Though all researchers agree natural sleep is best, military operational requirements at times makes getting sufficient, productive sleep impossible. Army researchers, then, also study sleep-inducing compounds to help circumvent the body's circadian rhythm, the internal clock that makes humans most sleepy between 3 and 5 a.m. and in the mid afternoon.

Though highly addictive, drugs called hypnotics do increase sleep length. However, if the user is awakened an hour or two after some drugs' peak effects, his or her judgment is impaired. If the user is a soldier, that means readiness is impaired.

The Army's aviation community at the U.S. Army Aeromedical Research Laboratory began testing zaleplon, a new sleep-inducing compound Feb. 23 to see if its hangover effect is less than previously tested hypnotics.

"Aviators, like the instructor pilots we have at Fort Rucker, can fly all days then 'poof' they're asked to switch to night flights, and they have real trouble staying awake and sleeping when they need to," said researcher Dr. Pat Le Duc of USAARL. "Finding a safe hypnotic is one way we can mitigate some of the effects of the circadian mechanism."

She along with the team at the lab hopes the dozen aviators in the eight-day, seven-night study will answer whether a 10 milligram dose taken before an early bedtime will allow subjects to fall asleep faster and get better sleep. The team also hopes to learn if an increase in sleep length will increase alertness, lessen fatigue and offset the common declines in performance that typically occur when work begins early in the morning, which runs counter to the circadian clock. The aviators will complete cognitive tests, fly the lab's simulator, undergo sleepiness and electrophysiological evaluations and complete questionnaires on their mood.

Showing aviators the results of their tests is often an eye-opener, Le Duc said. "When they're sleep deprived, there's a real decrease in their performance that they don't notice. Most of them think they're not affected by losing sleep, but when they see the results on paper, they realize how poorly they performed," she said.

While waiting for answers on the best stimulant or hypnotic for warfighters, Belenky's advice on catching z's is clear cut. "Take the opportunity to sleep. Naps are wonderful," he said.

He advises commanders to organize their areas so sleep can occur. "I've tried to sleep in a big tent where every 20 minutes someone shook me awake, asking me if I was 'Smith.' It got so bad, we ended up sleeping with big signs that had our names on them so we'd be left alone," he said.

Read about DARPA's program on preventing sleep deprivation.