One of the widely known effects of coffee is to keep the eyes open for extra hours. But a new study suggests that caffeine actually has little to no effect on sleep.
The study, published in the journal Sleep, found that drinking coffee hours before going to bed has no effect on how long a person takes to fall asleep. It also did not affect the length of their sleep.
The findings support previous studies that suggested caffeine will not disrupt sleep. The latest study analysed data from 785 African American men and women.
Researchers said they selected the group because of the lack of studies focusing on African Americans and the health effects of coffee compared to efforts involving non-Hispanic Whites. But the team noted the public can still benefit from their findings.
“There is no reason to think that these findings are not generalisable to other racial or ethnic groups,” Christine Spadola, lead study author from Florida Atlantic University, told MarketWatch. “This is one of the largest investigations of the impact of alcohol, caffeine and nicotine to date with more than 5,000 nights of data.”
For the study, Spadola and her team provided each participant with a wrist watch that monitored and recorded their quality of sleep for an average of 6.7 nights. The researchers also required sleep diaries that should include details on their use of cigarettes and consumption of alcohol and any drinks.
Coffee appeared not affecting or disrupting the participants’ sleep even when consumed four hours before sleep. However, both nicotine and alcohol were linked to worse sleep.
Researchers said smoking significantly affected sleep during the study. The participants with insomnia and exposed to nicotine slept for just 42 minutes less, while other smokers got up more frequently during the night.
Alcohol was also found causing poor sleep among the participants. The beverage mainly reduced the body’s ability to go into deep sleep and commonly forced people to get up in the middle of the night to use the bathroom because of dehydration and filled bladder.
Researchers noted more studies are needed to see coffee, cigarettes and alcohol directly affect the body and sleep.
Source: Medical Daily