4 Amazing Effects of Caffeine (and One That’s Not So Great)

Oh, caffeine, you hold so much capacity for good … and bad. (Photo: Priscilla De Castro for Yahoo Health)

Ever have caffeine a little too close to bedtime and then spend an hour or two in bed tossing and turning? We’ve known for a while that this common stimulant has a significant impact on sleep, but new research published in the journal Science Translational Medicine sheds more light on just how big the effects really are.

Speaking of light, researchers compared the effects of caffeine on circadian rhythms to that of bright light, which is already a well-established mechanism for extending the circadian phase. Keeping five subjects under tightly controlled conditions for 49 days, they found that a caffeine pill at bedtime — roughly equivalent to a double shot of espresso — delayed that internal clock by 40 minutes, about half the effect of bright-light exposure.

So, yes, you should definitely avoid that latte before bed. However, this study isn’t all bad news. The scientists say presleep doses of the stimulant might be useful in the right contexts. For instance, caffeine might be able to temper the effects of jet lag by resetting the circadian clock after jumping time zones during international travel.

Cool, right? With that, let’s check out some of caffeine’s other powerful effects on the body.

Caffeine can enhance memory

According to researchers at Johns Hopkins University, caffeine might help boost your memory for at least up to 24 hours. Participants in a double-blind study took either a 200-milligram tablet of caffeine or a placebo just five minutes after studying a compilation of photos.

When they tested the subjects the next day to see what they remembered, more of the caffeinated subjects were able to flag items that were “similar” to what they saw previously, yet not the same. The scientists say this “pattern separation” indicates a “deeper level of memory retention.” Most other studies focusing on caffeine and memory had participants consuming caffeine prior to their study periods, making it tough to account for potential compounding factors that might have happened after the tests.

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Caffeine may boost your naps

While this might sound weird, interesting 2014 research shows that caffeine can turn your power naps into super-powered naps. How? It’s all about the interplay between the caffeine and adenosine, a chemical compound that causes you to feel sleepy as a day wears on.

Adenosine builds up in your brain while you’re awake and drops again while you sleep. Since caffeine’s effects are greatest roughly 30 minutes after you consume it, if you take a 20-minute power nap, you’ll wake up right around the time your energy boost is peaking and adenosine levels have fallen significantly. In essence, you’ll feel even more alert than without that cup o’ joe and have yourself an ultimate power nap.

Caffeine can charge up your workouts

Stopping at Starbucks before hitting the gym might be a good idea, according to a small 2014 study in the Journal of Applied Physiology. In a sample of 14 healthy adults, participants who consumed the caffeine equivalent of two 8-ounce cups of coffee reported that their stationary bike workout was easier than those who took the placebo.

Interestingly, researchers also looked into how caffeine might influence diet later in the day. After tracking the participants’ food intake, they found that the caffeinated men and women ended up eating 72 fewer calories at lunch than the placebo group.

Related: Your Body Within an Hour of Drinking a Cup of Coffee

Caffeine may reduce erectile dysfunction

Could caffeine even be a simple fix for erectile dysfunction, a problem that affects millions of American men? Perhaps. In a study published in PLOS ONE, researchers from the University of Texas Health Science Center discovered that men who consumed between 85 and 170 milligrams of caffeine, or roughly one to two cups of coffee per day, were about 42 percent less likely to experience ED.

According to the scientists, caffeine likely helps relax specific arteries and muscles in the genitals that help increase blood flow to the region.

While science is showing caffeine has some powerful potential effects, the official recommendation is that you shouldn’t exceed 400 milligrams per day, which is basically equivalent to four cups of brewed coffee. If you do, you might experience side effects like heart palpitations, irritability, stomachache, or “the jitters.” So sip on, but with caution.

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