Consuming high-fat meals cause daytime drowsiness, a new study has revealed.

For a year, researchers from the University of Adelaide, studied the dietary habits of 1,800 Australian males aged 35 to 80 years old and found that participants with the highest consumption of fat are more likely to experience daytime sleepiness.

Study participants were asked to fill out a food-frequency questionnaire. They were also subjected to an electronic monitor for obstructive sleep apnea (OSA). Other factors that may affect sleepiness like smoking, alcohol consumption and physical activity were adjusted accordingly.

The study showed that 41 percent of those who took a high-fat diet reported daytime sleepiness, while 47 percent said they had trouble sleeping.

What concerns the researchers is that as much as 79 percent of the participants have sleep apnea, or have shallow breathing or pauses in breathing while asleep. Approximately 54 percent had mild to moderate sleep apnea, while 25 percent had moderate to severe cases of sleep apnea.

"This has significant implications for alertness and concentration, which would be of particular concern to workers," said study author and University of Adelaide Ph.D. candidate Yingting Cao. "High fat intake was also strongly associated with sleep apnea."

It is also important to note that high-fat intake's correlation with sleep apnea was more significant in participants with high body mass index (BMI).

In the U.S., those who work out on the road, such as truck drivers, railroad workers and bus drivers are required to undergo a sleep apnea test in an effort to reduce the number of vehicular accidents secondary to daytime drowsiness.

Cao explained that those who experience daytime sleepiness because of their high-fat diet tend to be sluggish. To counter it, they would resort to high-carbohydrate and high-fat diet - a vicious cycle. She also acknowledged that meal timing could also have an effect.

"But we have reason to believe that circadian rhythm, hormones and diet all work together to create these effects," said Cao.

The study was published in Nutrients.

Photo: Kim Ahlström | Flickr