The most commonly discussed symptoms of obstructive sleep apnea (OSA) may seem more frustrating than detrimental— snoring and fatigue— but this sleep disorder, in which an individual stops breathing repeatedly during the night, can have a major impact on health and cognitive function. In one recent study, which appear in the American Journal of Respiratory and Critical Care Medicine, researchers from the University of Louisville discovered that certain compounds found in green tea may help reduce cognitive deficits caused by OSA.

In OSA, muscles in the back of the throat relax and restrict the airway, causing a reduction in blood oxygen levels. The brain quickly wakes the body so that breathing can resume, and this cycle can occur as often as 30 times in an hour, significantly disrupting sleep. To replicate this pattern in rats, the researchers repeatedly exposed 106 male rats to brief oxygen depletion during 12 hour periods, reproducing the experience of those with OSA. During this time they divided the rats into two groups. While one group received ordinary drinking water, the other was given water mixed with catechin polyphenols, a kind of antioxidant found in green tea. This treatment appeared to protect the rats from the cognitive problems caused by oxygen deprivation, as they performed significantly better on a maze intended to test their memory and learning.

Many health benefits have been attributed to green tea, from preventing heart disease to improving the symptoms of Alzheimer’s disease, and research on green tea has focused on its antioxidant properties as the reason behind these potential effects. Past studies have also shown that oxygen deprivation caused by OSA may lead to oxidative stress, which is marked by an increase in free radicals, the harmful molecules that destroy cells. This may in turn contribute to cognitive problems. Antioxidants destroy free radicals, and in this study they appeared to play a large role in preventing cognitive deficits in the rats. Rats given plain water showed an increase in the molecular signs of oxidative stress, while rats given water with catechin polyphenols did not develop these signs and were better able to complete the maze.

While the results of this study indicate that green tea may provide some benefits for individuals with OSA, the researchers stress that green tea should not be used to replace other forms of treatment, which are intended to keep the individual breathing consistently throughout the night. OSA can have substantial consequences on cognition, and any substance that could offer relief should be studied in greater detail using human subjects. Still, factors other than oxidative stress may be involved in the cognitive deficits associated with OSA, and researchers should continue looking for treatments that can not only help those struggling with OSA to maintain their cognitive abilities, but also help them sleep better and breath steadily.