Results of a small trial suggest that melatonin may help people at high altitudes fall asleep faster, sleep better, and even think better, researchers said last week at SLEEP 2013, the annual meeting of the Associated Professional Sleep Societies LLC, in Baltimore, MD.
"This is important because many high altitude climates are extreme and dangerous. Climbing and military operations may require split-second decisions," primary investigator Dr. Christopher M. Jung of the University of Alaska at Anchorage told Reuters Health by phone.
These results are especially applicable to the 140 million people worldwide who live above 8,000 feet, he added.
Dr. Jung and his research team conducted a placebo-controlled, double-blind crossover trial with 13 climbers (mean age, 34), including two women, at 14,200 feet on North America's highest peak, Denali, in Alaska.
On two consecutive nights, each climber wore a wireless sleep recording device that measured sleep quality, and the next day took a Stroop word and color identification test that assessed cognitive performance. Each climber received melatonin one night and placebo the other night, in unknown sequence, ninety minutes before bedtime.
"Surprisingly, after taking placebo, the climbers in our study fell asleep after about 44 minutes, but after taking melatonin, they fell asleep in about 20 minutes. This increase in sleep was likely a significant factor in improving their cognitive performance," he added.
On the night climbers took melatonin, they had significantly less wakefulness after sleep onset (WASO) and decreased sleep onset latency (SOL), and on the following day they did significantly better on the Stroop test than those who took placebo (p<0.05). Their cognitive performance, measured as reaction time, was also significantly better (p<0.05).
"Melatonin has never been studied at altitude and this is the first setting I've seen that shows improved cognition with the drug at altitude," Dr. Jung said in his interview.
"When people go to altitude they tend to sleep worse, so this can improve their sleep and cognition. To put it in perspective, this affects not only climbers, but military personnel and others, including skiers. At Breckenridge Ski Resort in Colorado, alone, which goes up to 13,000 feet, 1.6 million people ski every year," he said.
Dr. Jung hopes to find in future studies that melatonin helps with blood pressure at altitude, and with free radical release from hypoxia.
In the meantime, he suggests that melatonin may be a promising and useful natural over-the-counter dietary supplement. "It should not be used instead of prescription drugs that help with high altitude, but could be used in addition to them," he said.
Dr. W. Christopher Winter, who directs the Martha Jefferson Hospital Sleep Medicine Center in Charlottesville, Virginia, and wasn't involved in this trial, said in an email, "What is so interesting about this study is that, to my knowledge, little to nothing is known about melatonin as a countermeasure to the effects of high altitude sleep and cognition. We have a body of information about melatonin and sleep, and we have a body of information about altitude effects on sleep and cognition, but this study gets the ball rolling on melatonin and its effects on high altitude sleep and cognition."
Dr. Winter had some questions. "I wonder how sustainable these finding would be over a longer period of time," he said. And, he added, "We know that in some patients, melatonin helps with their sleep. In this study, is the melatonin acting in any way to counteract the altitude effects or is the subject just sleeping better? In other words, could other sleep aids besides melatonin do the same thing? Also, given melatonin's ability to affect circadian rhythms, I wonder about timing, light exposure and other factors during the study, as well as the intrinsic chronotype of the subjects."
