— -- Navy SEALs may be some of the toughest people on the planet, but even an elite soldier doesn't do well without sleep.
Stew Smith, a former Navy SEAL, said he survived for three days on no sleep before the hallucinations started to set in. After about 72 hours of sleep deprivation during training, Smith recalls mistaking an airplane for a flying horse, perceiving a bridge as a giant Pez dispenser, and seeing a squat, muscular body builder where there was in fact a fire hydrant.
But he wasn't quite done. Smith and his crew had another two days of running, swimming, paddling, climbing and plunging into freezing water. In total, he and his team had to stay awake for a punishing five days as part of their Navy SEAL training.
“I would be thinking of something and I would see it in front of me like a cartoon character,” he recalled, describing his hallucinations. “When you’re losing sleep, after a while you turn to this fight-or-flight response. You just go into survival mode.”
At the time, Smith said he survived by staying in constant motion, staying uncomfortable, and psychologically breaking each day into a series of six-hour stretches until the next meal.
While SEALs may need to stay awake for days in life-or-death situations, Smith said he would never wish this kind of sleep deprivation on anyone. ABC News' own Dan Childs, head of the Medical Unit, is currently staying up for 40 hours as part of the "Good Morning America" 40th anniversary event to show how important sleep is. That's half of the time Smith was required to stay up.
Dr. Kirk Parsley, another former SEAL who is also a physician specializing in sleep health, couldn’t agree more.
Follow All of Dan Childs' Adventures on the Live Stream Below:
To improve sleep hygiene, Americans can try to go to bed at the same time each day, get those phones out of the bedroom, make sure sleep environments are dark, quiet and cool -- and most importantly, take the crucial first step of deciding that sleep matters.
“Your health, well-being, longevity and success can really be broken down into four pillars: sleep, nutrition, exercise and stress mitigation,” Parsley said. “These four are all equally important -- like the tires on a car. Would you take off one of your car tires? None of those tires are optional.”
So unless you're pulling a stunt like ABC News' Dan Childs -- for the sake of science and in a carefully monitored sleep lab -- put down the screen you're reading this on, put on your PJs, and go get some sleep.