When 3 p.m. rolls around and your energy levels dip, you might reach for a cup of coffee to get you over the hump. While your afternoon mug will perk you up in the present moment, odds are you'll also pay the price for it later in the day.
Yep, when we look to our midday brew for a boost, it often screws with our sleep at night.
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We spoke to dietitian May Zhu, RDN, LDN, founder of Nutrition Happens, to get the scoop on why sipping the hot stuff to stave off an afternoon slump is really bad for your sleep and what else you can do for a little oomph when the late day lethargy hits.
5 Ways Coffee Can Affect Your Sleep
1. It Makes You Jittery
Considering a morning cup of joe gives you a jolt of energy, you might lean on your java to help you get through a midday slog. After all, "coffee contains caffeine, which is a stimulant that causes you to feel more awake and alert," Zhu says.
But the same amount of caffeine midday may give you the jitters. Feeling jittery, nervous or having a racing heart can all be signs that you're drinking too much for your body, Zhu says.
And being amped up so close to nighttime isn't going to do you any favors in the sleep department.
2. It Can Disrupt Your Body's Natural Rhythm
"Since caffeine stimulates the central nervous system to keep you alert and awake, consuming it closer to bedtime can disrupt the total amount of deep sleep that we need to feel refreshed," Zhu says.
"It might also make it harder for you to fall asleep, which may shift your body's natural sleep/wake pattern," she adds.
Indeed, a February 2017 systematic review in Sleep Medicine Reviews found that caffeine not only prolonged the time it took for people to fall asleep but also reduced the amount and quality of sleep. Basically, caffeine intake also led to more wakefulness and sleep disturbances.
Thing is, if your afternoon coffee drinking becomes a habit, it can harm your health in the long run. Insufficient sleep is associated with a higher risk for depression, diabetes and heart problems, according to Harvard Health Publishing.
3. It Can Make You Pee More During the Night
If you find yourself waking from slumber to run to the bathroom, your late-day cup of coffee could likely be the culprit. Caffeine has mild diuretic effects, which means it may cause you to pee more frequently, Zhu says.
But interrupted sleep doesn't fare well for your daily functioning. In fact, sleep disruptions can impair cognitive performance during the day, according to a September 2014 study in Psychology and Aging
4. It May Make Night Sweats Worse
Many people associate night sweats with factors such as anxiety, menopause or various medications, but getting too much caffeine midday may also contribute to sweaty sheets, too, Zhu says.
What's more, if you're going through menopause, caffeine might increase the severity of your night sweat symptoms. A February 2015 study in Menopause found a link between caffeine intake and a rise in night sweats (and hot flashes) in menopausal people.
If you're experiencing frequent night sweats, see your doctor to rule out any underlying medical issues.
5. It Might Contribute to Late-Night Hunger and Overeating
"Some studies have shown that caffeine can have appetite-suppressing effects, particularly when consumed 30 minutes to 4 hours before a meal," Zhu says.
But here's the issue: If your afternoon brew hampers your hunger at lunch or dinner (and decreases what you eat at these meals), you might end up feeling ravenous later and eating more than you intended.
"Remember, eating enough balanced meals with protein and fiber-rich carbohydrates throughout the day can help prevent overeating at night," Zhu says.
Not to mention, a grumbling tummy is also another surefire way to prevent you from drifting off to dreamland.
When Should You Stop Drinking Coffee During the Day?
To reduce these sleep-sabotaging effects, put a cap on your coffee intake.
While a caffeine high hits your body within 30 to 60 minutes, the stimulant has a half-life of up to five hours, according to the American Academy of Sleep Medicine. This means it can take as long as five hours for your body to remove half of the drug.
Still, the remaining caffeine can linger in your system for much longer and potentially disrupt sleep. Case in point: A November 2013 study in the Journal of Clinical Sleep Medicine found that having caffeine even six hours before bed reduced sleep by more than one hour.
Matter of fact, "depending on how your body metabolizes caffeine, it can take up to 10 hours for it to completely clear from your system," Zhu says. So, to be safe, you should allocate 10 hours to allow your body to flush it out.
That means, if you plan to hit the sheets at 11 p.m., your last cup of coffee should be no later than 1 p.m.
How Much Caffeine Is Safe?
“One cup of coffee contains around 95 milligrams of caffeine, and, for most adults, up to 400 milligrams of caffeine appears to be safe for consumption,” Zhu says.
But caffeine sensitivity and metabolism can vary by the individual, she adds. That means, for some people, even light doses of caffeine can have greater effects. So, pay attention to your body. If two cups early in the day still make you feel wired later into the night, adjust your intake as needed.
Need a Late Afternoon Energy Boost? Do These Things Instead
Most of us reach for coffee when our energy levels drop midday. But it's not the only (or best) option for putting a bit of pep in your step. When the afternoon slump starts to slow you down, try these energizing tips instead:
1. Stay Hydrated
"Fatigue is a common sign of dehydration," Zhu says. "Staying hydrated with caffeine-free drinks such as water, sparkling water or even herbal teas such as chamomile or peppermint can all count towards your daily hydration."
2. Get Up and Stretch
A quick stretch session can serve as a perfect pick-me-up. Yep, dynamic stretching will get your blood pumping and help lift your energy levels when they're low.
3. Eat Balanced Meals
Eating balanced meals throughout the day helps ensure your energy levels stay steady, Zhu says. "Aim for a combination of protein and fiber-rich carbs to keep you satiated and your blood sugar stable to avoid the afternoon energy crashes," she says.
So, Is Drinking Coffee in the Afternoon That Bad?
While an afternoon brew will give you a buzz, it's also likely to delay your sleep. Always heed your body.
If you notice your sleep is compromised, it might be time to ax your afternoon coffee habit — or at least take your last sip a tad earlier in the day.
Remember, to be safe, give your body about 10 hours to flush out caffeine — so drink your last cup of coffee about 10 hours before you plan to go to bed.
- Harvard Health Publishing: “Blue light has a dark side”
- Psychology and Aging: “Role of sleep continuity and total sleep time in executive function across the adult lifespan”
- Menopause: “Caffeine and menopausal symptoms: what is the association?”
- American Academy of Sleep Medicine: “Sleep and Caffeine”
- Journal of Clinical Sleep Medicine: “Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed”
- Sleep Medicine Reviews: “Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials”