The Coffee and Mortality Connection: Too Much Coffee Can Be Serious

A new study suggests that too much coffee may have more serious consequences than the occasional night of tossing and turning.
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Do you rely on several cups of coffee throughout the day to keep yourself focused and alert? Many people start the morning with a cup of hot coffee and then continue to drink it all day long. It's no secret that caffeine can interfere with sleep. Once ingested, the stimulant effects of caffeine go into effect quickly and stay in the body for several hours. Drinking caffeinated beverages like coffee even several hours before bedtime can compromise sleep.

A new study suggests that too much coffee may have more serious consequences than the occasional night of tossing and turning. A team of researchers from the United States and the United Kingdom looked at the possible relationship between coffee consumption and mortality risks -- both general mortality and cardiovascular mortality -- in adult men and women. They found links between heavy coffee drinking and general, all-cause mortality in men and in women under the age of 55. This association between heavy coffee consumption and mortality was particularly strong for both men and women under the age of 55.

Researchers used data from the Aerobics Center Longitudinal Study, a large-scale, long-term study of health and fitness. Researchers included 43,727 subjects in their coffee-mortality investigation, men and women ranging in age from 20-87. They excluded people with a history of serious illness, including cardiovascular disease, stroke, and cancer. Researchers examined follow-up data on their subjects for an average of 17 years. Over this study period, 2,512 deaths occurred among the study population. Of them 804 deaths -- 32 percent -- were attributed to cardiovascular disease. Coffee consumption was measured through questionnaires and was based on an 8-ounce cup size.

Researchers analyzed the data on mortality in relation to coffee consumption, while making adjustments to rule out the influence of other potentially contributing factors, including physical activity, age, and cardiovascular fitness. They found significant increases to general, all-cause mortality risks for men who drank coffee heavily, and also for women under the age of 55 who were heavy coffee drinkers:

  • Among the total population of men in the study, those who drank more than 28 cups per week -- an average of four 8-ounce cups per day -- had a 21 percent increased risk of all-cause mortality.

  • Among men under 55 years of age, those who drank more than 28 cups of coffee per week had a 56 percent increased risk of all-cause mortality.
  • The overall study population of women showed no association between heavy coffee consumption and mortality. But for women under the age of 55, drinking more than 28 cups of coffee per week was associated with a 113 percent increase in all-cause mortality risk.
  • Researchers found no statistically significant association between coffee consumption and cardiovascular mortality among men or women.
  • Previous research has returned conflicting results on coffee's effects on health. Some studies have demonstrated links between coffee consumption and cardiovascular and other cause-specific mortality rates. Other studies have indicated that drinking coffee may provide benefits to health, and lower mortality risks.

    The conflicting data on coffee's impact on health can be confusing. This latest study is compelling for several reasons. The size of the study group and the duration of the study period are significant. (In tracking more than 43,000 people for an average of 17 years, researchers analyzed nearly 700,000 person-years of follow-up data.) Also significant is the wide age range among the subjects, capturing early, middle, and late adulthood. Researchers also did a good job of attempting to isolate the association between coffee drinking and mortality risk, by excluding people with health problems at the study outset, and by controlling for other potential contributing factors to mortality risk. What this study did not explore -- and what future research will undoubtedly investigate -- are the possible mechanisms by which coffee may contribute -- directly or indirectly -- to health problems and increased risks of mortality.

    Will coffee's impact on sleep be a factor? We'll have to wait and see. Anyone who's ever had a late-day cup of coffee only to find themselves wide awake that night knows that heavy and ill-timed caffeine consumption can interfere with sleep. This doesn't mean that coffee and other caffeinated beverages have to be completely off limits. Moderate coffee drinking has not been linked to health problems and may even provide health benefits. Enjoying a cup of coffee does not have to interfere with sleep for most people, as long as you're smart about how much, and when, you consume it. Looking for ways to moderate your coffee drinking habit? Here are some strategies that can help keep your coffee consumption in check -- and help protect your sleep:

    Consume caffeine early in the day. I advise my patients to make their most caffeinated beverage of the day one they consume earliest. For most of us, that's the cup of coffee we go in search of after rising from bed. Rather than going back to the coffee machine to fill up throughout the day, plan to gradually switch over to less caffeinated and caffeine-free beverages, including decaf coffee and teas, as the day wears on.

    Be caffeine-free by mid-afternoon. It can take as much as eight hours for the caffeine in a single cup of coffee to leave your system. I recommend putting no less than that amount of time between your last caffeinated beverage and your bedtime. If you turn in at 10 p.m., be caffeine-free by 2 p.m. in order to protect your ability to fall asleep.

    A cup is A CUP. When I talk about drinking a cup of coffee, I am referring to an actual 8-ounce cup. So are the researchers in this study. Don't kid yourself about how much coffee you're really drinking. Some coffee places sell 16, 20, 24 or even 28-ounce "cups" of coffee. With one of these beverages you can meet or exceed the recommended maximum daily amounts of caffeine. The National Sleep Foundation recommends no more than three 8-ounce cups of coffee per day.

    If you're a coffee lover, or a regular coffee drinker, don't panic. It may be time to take a fresh look at your coffee habit, and depending on how much you're drinking to scale back a little. Be smart about your coffee consumption and you can enjoy your cup of joe while also taking care of your sleep and your overall health.

    Sweet Dreams,
    Michael J. Breus, Ph.D.
    The Sleep Doctor®

    Everything you do, you do better with a good night's sleep™

    Twitter: @thesleepdoctor @sleepdrteam

    For more by Dr. Michael J. Breus, click here.

    For more on sleep, click here.