Science Says When to Stop Drinking Coffee to Ensure a Good Night's Sleep. And It Is Earlier Than You Think.You might think that enjoying your last cup of joe in the late afternoon is enough to avoid adverse sleep effects, but science says otherwise.

If you're like most Americans, you start your morning by reaching for the hot cup of coffee—or several—that gives you the energy boost necessary to get through the day; 62% of people in the U.S. drink some form of the beverage every day, with consumption increasing in the younger demographic, according toReuters.

You've probably heard that caffeine can disrupt your sleep, but many people think that downing their last cup in the late afternoon, or even in the early evening, is early enough to avoid any adverse effects come bedtime. Unfortunately, the science says otherwise:Independentcites research suggesting that you should hold off on the magical bean brew once 2 p.m. rolls around, or at least seven hours before you plan to go to bed.

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In a study published in theJournal of Clinical Sleep Medicine, consuming caffeine in the six hours before bed won't necessarily keep you awake, but it will reduce your quality of sleep. It also wreaks havoc on your body's internal clock, mimicking the effect of jet lag. According to another study published inScience Translational Medicine, enjoying a double espresso three hours before bed (or its equivalent, approximately 60-100mg of caffeine) can wind your body's clock back by nearly an hour.

When it comes to howmanycups you should be drinking per day, theMayo Clinicrecommends about four, which should approximate 400mg of caffeine.

Soda- and energy drink-lovers should take note of these findings too—caffeine is caffeine, which means that the suggested 2 p.m. cutoff also applies.

What's the big deal? Disrupting the body's clock does more than leave you feeling groggy the next day; it's also been linked to heart disease and neurodegenerative disorders like Alzheimer's.

It's not all bad news though: As long as you get your java fill between 10 a.m and noon—the window of time when that rush of caffeine is most needed and most effective—you can reap the rewards of your daily habit without worrying about the costs.

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