New Study: If You Mix These 2 Beverages, You’re Wrecking Your Sleep Health

Morning coffee and evening wine are rituals as old as time—but scientists just had a major awakening about what happens when you drink them in combo.

Search espresso martini recipe and you’ll find 28 million results on Google alone—but if you’ve ever had just one too many of this drink that kicks off or closes down a fun night in equal measure, you know the effect of this sugary, caffeinated cocktail can make for an exhausted next day.

As a festive time of year approaches, psychology and psychiatry researchers from the University of Washington (UW) and the University of California, Berkeley, examined the interplay between caffeine and alcohol among a unique participant group: Financial traders. Known for their high-pressure roles and decadent downtime—and given their general routine consumption of both coffee and alcohol—this group provided a prime lens to observe the substances’ effects on sleep.

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The researchers’ findings were  published November 2023 in the peer-reviewed scientific journal PLoS ONE. Here’s how the study worked: The traders took time out to log their daily intake of coffee and alcohol, along with detailed notes on their sleep quality and duration. This allowed the researchers to examine how caffeine and alcohol affected sleep both independently and in combination.

The results initially caught the researchers off guard, particularly concerning how these substances interact and affect daily life.

The impact of alcohol on sleep

A noteworthy revelation from this study was a 4% decrease in sleep quality following alcohol consumption. This is particularly significant for individuals in high-stress professions who might use alcohol to decompress, perhaps unaware of its negative impact on essential rest.

This data echoes previous studies that narrowed in on the disruptive nature of alcohol on the sleep cycle. A 2018 study indicated that even low alcohol consumption (less than two servings per day for men or one for women) led to a 9.3% decrease in sleep quality. Moderate consumption doubled this effect, and high consumption nearly quadrupled it.

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Coffee and sleep duration

Caffeine wakes you up, right? Of course the role of caffeine on sleep has been the subject of numerous studies, which have consistently shown that caffeine delays sleep onset, trims total sleep time, and detracts from sleep satisfaction.

In this particular research, an intriguing pattern emerged: Each cup of coffee consumed the previous day correlated with a 10-minute reduction in sleep duration. While seemingly minor, this reduction can accumulate, potentially leading to chronic sleep deprivation. Especially during busy periods, that early-morning cup, plus the one that helped you power through the afternoon, followed by one after dinner and wine, could quickly equate to a half-hour of restlessness during that already-precious window for sleep.

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The unexpected finding

This is where the findings got particularly intriguing. The researchers initially hypothesized that the combination of daytime caffeine and nighttime alcohol would magnify negative effects on sleep.

The actual findings, however, presented a complex picture. Despite a measurable reduction in sleep duration from caffeine, participants did not perceive a decline in sleep quality. This suggests a nuanced interplay between coffee and alcohol and the need for further investigation.

Frank Song, the study’s lead author and fourth-year clinical psychology doctoral candidate in the UW Department of Psychiatry and Behavioral Sciences, remarked in a press release: “It’s a very, very nice thought, I think, in many people’s minds that you could just use caffeine to wipe off the hangover. But what we find is that while there may be greater alertness in the short term, it creates a sleep-state misperception contributing to continued use despite negative effects on sleep.”

This suggests a cycle of “self-medication” in which alcohol is used to counteract the effects of caffeine and vice versa—a pattern that may seem beneficial in the short term but could have long-term consequences for sleep health.

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The takeaway

If you’re caught in a routine of using alcohol to relax at night and then relying on coffee to stay alert during the day, it might be time to reevaluate. This pattern, seemingly harmless, could be subtly undermining your sleep quality. Given sleep’s critical role in overall health, fostering habits that promote rather than impair sleep quality is crucial. If changing these habits is becoming a challenge, consider seeking guidance from a healthcare professional or a sleep specialist for tailored advice and support.

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Dr. Patricia Varacallo, DO
Tricia is a doctor of osteopathy with experience in primary healthcare. She received her medical degree from the Lake Erie College of Osteopathic Medicine and conducts clinical research in Sports Medicine and Orthopedics, as she is motivated by the desire to contribute to the development of innovative treatments and therapies. She is also a certified lifestyle coach for the CDC-recognized National Diabetes Prevention Program, empowering individuals to make lasting, healthy lifestyle changes. Dr. Varacallo loves to write— especially about health, wellness, and grief. Drawing from her own experiences of loss and caregiving, she loves to offer support and encouragement to those navigating their own grief journeys. Outside of her professional life, she enjoys traveling and exploring the sunny beaches of Florida with her significant other, always ready for their next adventure.