Researchers from Rush University Medical Center, Brigham and Women's Hospital and Harvard Medical School have discovered that caffeine works by thwarting one of two interacting physiological systems that govern the human sleep-wake cycle. The researchers, who report their findings in the May issue of the journal SLEEP, propose a novel regimen, consisting of frequent low doses of caffeine, to help shift workers, medical residents, truck drivers, and others who need to stay awake get a bigger boost from their tea or coffee.
"I hate to say it, but most of the population is using caffeine the wrong way by drinking a few mugs of coffee or tea in the morning, or three cups from their Starbuck's grande on the way to work. This means that caffeine levels in the brain will be falling as the day goes on. Unfortunately, the physiological process they need to counteract is not a major player until the latter half of the day," said James Wyatt, PhD, sleep researcher at Rush University Medical Center and lead author on the study.
Though many studies have measured caffeine's sleep-averting effects, most do not take into account that sleep is governed by two opposing but interacting processes. The circadian system promotes sleep rhythmically--an internal clock releases melatonin and other hormones in a cyclical fashion. In contrast, the homeostatic system drives sleep appetitively--it builds the longer one is awake. If the two drives worked together, the drive for sleep would be overwhelming. As it turns out, they oppose one another.
Caffeine is thought to block the receptor for adenosine, a critical chemical messenger involved in the homeostatic drive for sleep. If that were true, then caffeine would be most effective if it were administered in parallel with g
Contact: Chris Martin
Rush University Medical Center