It will come as no surprise to most with military experience that two-thirds of all U.S. service members do not get enough sleep to be considered healthy. And while Army sleep researchers realize that troops often can’t get more sleep, they recently put a group of volunteers through a 48-hour sleepless experiment to test a device they hope will help them recover faster whenever they do get some shut eye.
“Two thirds of service members do not sleep enough every night, a rate that’s twice as high as the civilian population,” said Dr. Tracy Jill Doty, the chief of Walter Reed Army Institute of Research’s Sleep Research Center. “If they can only sleep for two hours, is there a way that we could make their sleep better?”
To do that, researchers are looking at transcranial electrical stimulation, a technique that sends electric pulses through electrodes attached to the head to guide a sleeper’s brain into a state of deeper rest and quicker restoration. The goal is to induce a state of slower electrical activity, which researchers described as ‘slow waves.’
Ultimately, researchers say, they want to apply their research to a headband-style device for field use by soldiers that they can use on deployments and extended training, or whenever operational demands put sleep at a premium.
With the electrical stimulation, researchers are “basically coaxing the brain into something that it’s already doing,” Doty said. “We’re actually taking something that the brain already does and just helping it, get there a little bit faster and stay there a little bit longer.”
A 48-hour sleepless experiment
In the last twenty years, researchers have found that the state of ‘slow waves’ during sleep improves the brain’s performance. A 2006 study found that 25 minutes of stimulation by slow waves in the first half-hour of sleep improved test subjects’ ability to recall word pairs they learned before going to sleep.
With this understanding, Dr. John Hughes, WRAIR senior sleep researcher thought: Can they improve the quality of sleep, especially short periods of time, and make it more restorative?
“It really seemed like it could translate into this methodology of using transcranial electrical stimulation to enhance the slow waves because what the science was revealing was that the slow waves of sleep are what conveys its recuperative or restorative function,” Hughes said. “If we could enhance that we might be able to enhance the restorative capacity in a given period of time.”
For the study, participants were allowed to sleep for two hours before entering a 48 or 46-hour period of sleep deprivation – conditions “similar to what might happen in combat,” Hughes said. During that pre-wake sleep, participants were given electrical stimulation or fake stimulation (as a placebo) in their second hour of sleep before they were woken up. Participants then took a psychomotor vigilance test, which is known to be extremely sensitive to sleep loss.
“Those individuals who received the stimulation fared much better during that subsequent period of sleep deprivation. That is to say, they didn’t experience the same severity of a deterioration in performance like people normally do when they’re sleep deprived,” Hughes said.
Individuals who received slow wave stimulation maintained their performance “substantially better than those who did not receive the stimulation,” Hughes said. They also found that even after 46 hours of sleep deprivation, those who received the slow oscillatory stimulation “got right back to their baseline performance with one night of recovery sleep.”
“Whereas even after two nights of recovery sleep, the individuals who did not receive the stimulation, we’re still not back to performing at their baseline like how they would perform the day before the sleep deprivation.”
The high cost of bad sleep
Long before Doty and her team began their studies, the military sought ways to improve sleep for troops, often with mixed results. The Government Accountability Office once described previous DOD efforts to combat fatigue as “fragmented” with duplicative, wasteful research across the services.
Besides the fact that sleep is important for everyday functioning, a lack of sleep can be costly.
A 2017 collision between the Naval Destroyer USS John S. McCain and a commercial ship was found to have occurred when sleep deprived crewmembers made key mistakes. The accident killed 10, injured 48 and caused $100 million in damages.
“While combat and other non standard operations may require crew members to forego adequate rest for short periods, relying on fatigued crew members to accomplish normal daily tasking introduces unnecessary risk,” the National Transportation Safety Board maritime accident report said.
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The period of sleep that researchers are interested in is “non-REM” sleep which our brains prioritize and makes up roughly 20% of an eight-hour sleep period.
While REM sleep was previously thought to be the best for learning and memory, non-REM sleep – which produces the slow waves – science is finding, is more important for memory consolidation. During this kind of sleep, the slow brain waves help eliminate excess brain connections that “take a metabolic toll” and “actually decrease performance,” according to Hughes.
“When you have too many connections, they can lead to some of the symptoms that people experience during sleep deprivation because there are simply too many. The brain is a little bit too hyper connected.”
Researchers are effectively trying to “transform light sleep into deep sleep.” Now that WRAIR research has shown the positive effects of transcranial electric stimulation, they’re focused on applying it to technology that troops can bring into the field. That’s where the headband comes in.
The headband
Researchers are working on a headband that they hope soldiers might one day use in the field. Teledyne Scientific had originally worked with DARPA on a program to augment certain brain mechanisms during non-REM sleep for the purpose of improving memory. The study was not necessarily focused on improving sleep, but Stephen Simons, technical manager for Teledyne Scientific & Imaging said they’re pretty much one in the same.
“You really can’t kind of separate those two things. If you do improve sleep at least, studies have shown that when you improve deep sleep in particular that you do tend to get an improvement in memory,” Simons said.
In addition to applying their headbands to military settings, Teledyne is working to sell their headbands commercially for people who suffer with insomnia to fall asleep faster.
The full spectrum of wearable devices for sleep is still being discovered, Simons and WRAIR officials said.
While WRAIR’s research is currently focused on healthy individuals like active duty service members “to get to the ground truth of whether this works,” Doty said these devices could be applied in the short-term to insomnia or even the longer-term impacts of neurological and psychiatric disorders that are characterized by reductions in the slow wave activity during sleep.
“I kind of sound like a broken record but, tell me what the problem is and I can give you a sleep solution,” Doty said. “I know sleep will help it in some way.”
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