Studies show that alcohol and caffeine reduce the quantity and quality of sleep.

Despite their apparent benefits to sleep, a recent study reveals that alcohol and caffeine actually have the opposite effect. Getty Images / Yana Iskayeva

Sleep deprivation is seen by researchers as an underappreciated global health problem.

Alcohol is frequently used at night to aid in sleep and caffeine throughout the day to keep people alert when they have sleep problems.

Researchers at the University of Washington School of Medicine discovered that users of both drugs did not feel as though their quality of sleep had decreased.

Scientists surmise that this misguided view could set off an unconscious loop of self-medication that results in restless nights.

Researchers believe that sleep deprivation is an underappreciated global health issue.Reliable Source.

Previous research indicates that approximately one-third of the global populace suffers from symptoms of sleeplessness. Furthermore, up to 70 million Americans suffer from a sleep issue.

Caffeinated beverages are frequently consumed during the day by people who experience daytime fatigue due to inadequate sleep.

These same individuals might also use alcohol as a sleep aid at night.

This new study, which looks at how using both alcohol and caffeine affects total sleep, is the first that has been documented in the journal PLOS ONETrusted Source.

Even though each substance lowers reported sleep quality when investigated separately, researchers from the University of Washington School of Medicine discovered that study participants who drank alcohol at night and caffeine during the day did not perceive a decline in their sleep quality.

Scientists surmise that this misguided view could set off an unconscious loop of self-medication that results in restless nights.

Sleep, alcohol, and caffeine: What we now know

Frank Song, lead author of this study and a researcher in the Department of Psychiatry and Behavioural Sciences at the University of Washington School of Medicine, notes that while previous research has shown people the detrimental effects of alcohol and caffeine on sleep, no study has examined the combined effects of the two substances on sleep as people go about their daily lives.

Regarding alcohol consumption, a study released in October 2021 discovered that a higher alcohol intake was linked to shorter sleep duration and lower sleep qualityTrusted Source.

According to research released in December 2019, drinking alcohol disturbs sleep in a number of ways, including by exacerbating breathing-related sleep problems and causing circadian rhythm anomalies.

Regarding caffeine consumption during the day, a September 2023 study found that caffeine can postpone the onset of REM sleep.

Caffeine may also make a person feel and stay awake during the day, although long-term usage of the drug has been shown to impair overall sleep quality (Trusted Source).

Caffeine intake cuts down on sleep duration by ten minutes.

For this study, Song and his colleagues measured the sleep-related metrics and alcohol and caffeine consumption patterns of 17 male, full-time financial traders over the course of six weeks using computerised daily surveying methods.

"We decided to focus on financial traders since, as an investment analyst on Wall Street, I worked with many traders, and we know from research that this is an adult population that regularly consumes both caffeine and alcohol," Song told Medical News Today.

"They value alertness and mental acuity during the day, which I think represents the lifestyles of many working adults," he added. "Also, their profession requires high attention and cognitive speed."

When caffeine consumption was examined separately, researchers discovered that, on average, each cup consumed the day before decreased the amount of sleep that study participants reported getting.

Based on other studies on caffeine and sleep, Song stated, "We had anticipated we would find an actual caffeine-induced decrease in sleep duration." "The size of the reduction was larger than we had anticipated, which surprised us."

Additionally, they discovered that individuals who had alcohol the night before self-reported a 3% average decline in sleep quality.

Regular stimulant usage may conceal a deterioration in sleep quality.

The results differed slightly when researchers examined the effects of alcohol and caffeine usage on study participants' subjective quality of sleep.

According to Song, "it is challenging to quantify the interaction in the same way we interpret the individual effects of alcohol and caffeine on sleep quantity/quality."

That being said, he noted, "we discovered an interesting interaction where the sedative effects of alcohol consumption in the evening mitigated some of the detrimental impact of caffeine consumption during the day on sleep."

However, Song and his colleagues discovered that habitually using alcohol to counteract the stimulating effects of caffeine and vice versa points to research participants engaging in a self-medication behaviour.

People did not report a decrease in the quality of their sleep, despite the fact that coffee lowered the quantity of sleep they had, indicating a mismatch in perception. This could encourage people to keep self-medicating even while it interferes with their sleep. Put another way, a person's chronic use of the two drugs may conceal the deterioration in their quality of sleep, keeping them ignorant of it.

Frank Song, principal writer

Why using alcohol and caffeine as self-medication disrupts sleep

Following his examination of the study, Dr. John Saito—a pulmonologist at Children's Hospital of Orange County and a member of the Public Awareness Advisory Committee of the American Academy of Sleep Medicine—told MNT he was not taken aback by the results.

According to Dr. Saito, alcohol is a neurotoxic that depresses the central nervous system and impairs awareness of one's surroundings, making it a sedative for health .

“Sleep is not sedation. As mentioned, drinking alcohol right before bed severely interferes with getting a good night's sleep. Caffeine is a stimulant that lengthens our sleep duration by preventing our brain from sensing when we are sleepy. This enhances alertness.

John Saito, M.D.

"Taking medications for short-term symptom alleviation is not new, thus it was not surprising to find that drinking alcohol and caffeine simultaneously changed people's perceptions of how well their sleep was. Similar to repeatedly hitting your head against a wall, ingesting cannabis, and reporting that the pain was not as bad as you had anticipated, he said.

MNT also discussed this study with board-certified family physician Dr. Monique May, who serves as Aeroflow Sleep's medical advisor.

Physicians could utilise these statistics, according to Dr. May, to caution their patients about the risks associated with self-medication.

Given the possibility of alcohol addiction, she clarified, "there is a possibility that people will require more of either substance to balance themselves out, and that could become problematic."

"[People] should be aware that, while caffeine negatively affects sleep quantity, alcohol tends to negatively affect sleep quality."

Monique May, D.O.

It's also crucial to note that, albeit to a lesser extent than its impact on sleep quantity, coffee had a minor effect on the study's participants' quality of sleep. In spite of caffeine's detrimental effects on sleep, people may continue to take it because of this "mismatch in perception between sleep quantity and sleep quality," Dr. May continued.