Eachnight may earn commissions for products you purchase through our links. Our articles and reviews include affiliate links and advertisements, including amerisleep advertising. Learn more Updated May 18, 2021Coffee is one of the most widely consumed stimulants in the world, next to herbal teas. People turn to the drink for increased alertness, energy, and focus. However, in some cases, it can have the opposite effect and make you feel tired instead.In this article, we will talk about the different reasons why coffee can make you sleepy, provide tips for avoiding drowsiness after your daily coffee routine, and answer some of the most frequently asked questions about coffee. Let’s dive in!1. It Can Cause DehydrationCoffee is a diuretic, meaning it helps the body rid itself of water. Because of this, coffee drinkers sometimes find themselves in a vicious cycle of making frequent restroom visits.Once the body loses water and coffee officially causes dehydration, your blood volume decreases. The blood then travels much more slowly through veins and arteries, resulting in less oxygen being delivered to the body. Without enough oxygen, you experience exhaustion. To combat the tired feelings, you reach for another coffee. And so, the cycle continues.This pattern leads to dehydration and fatigue. If the body isn’t adequately hydrated, you could potentially feel tired after consuming coffee instead of energized. “Dehydration can be a definite cause of fatigue. To make sure you’re staying hydrated, you don’t just have to focus on water. You can have coffee in moderation, but you can also count a smoothie, soup, or hydrating foods like melon or berries towards your goal. Remember, you’ll need to focus more on hydration during hot summer months if you’re exercising strenuously, and especially if you’re sick.” says dietitian nutritionist Carlene Thomas RDN.The good news is, caffeine in moderation won’t cause dehydration. Keep your caffeine intake to 500 mg or less per day to take advantage of coffee as part of your hydration routine.2. It May Lead to a Sugar CrashIf you drink coffee or coffee-flavored drinks containing high amounts of sugar, it’s likely you’ll crash hard after a couple of hours once the quick energy runs out. This happens because the body processes sugar at a much faster speed than it does caffeine.Coffee beverages with lots of whipped cream or shots of flavored syrup are common culprits to avoid. Within 90 minutes of ingesting these sugary drinks (depending on what you ate recently), you could feel depleted of energy as the body’s blood sugar levels skyrocket and come crashing back down again.3. Your Adenosine Receptors are BlockedAdenosine is a chemical in the brain affecting the body’s internal clock. Our levels fluctuate throughout the day, increasing in waking hours and dropping while we sleep.Under normal circumstances, the adenosine binds to receptors in the brain that slow brain activity to prepare for rest. When you consume caffeine, however, it blocks these receptors and prevents the brain from receiving adenosine, so the chemical builds up. Once the effects of the caffeine wear off, the accumulated adenosine floods through the brain and causes feelings of fatigue.4. You Have a High Caffeine ToleranceFor those who drink coffee regularly or in excess, it’s possible to build up a tolerance to it over time. and that tolerance level may change due to a variety of factors including age, weight, and medications. Coffee is addictive, so the more you drink, the more you need to feel alert and focused. To prevent yourself from developing a tolerance, you will want to stick to drinking 500 mg or less of caffeine per day.5. Toxic ChemicalsMycotoxins are naturally occurring toxic chemicals produced by molds that grow on coffee, in grains, and peanuts among other foods. In high doses, these are very harmful to the body causing dangerous reactions ranging from inflammation of the lungs and difficulty breathing to high fever.To avoid consuming mycotoxins, the WHO recommends only using commodities that are properly dried and stored (which effectively prevents mold growth). Opt for buying coffee from wet-roasted coffee beans and choosing beans that are grown at high elevations when you can (specifically 100% Arabica beans) since mold is less likely to form in cooler, dryer climates. Aim to stay away from coffee “blends,” as well, because the origins of these are usually unknown, making it difficult to ensure the quality of the beans and their processing.How to Minimize the Negative Effects of CoffeeBy following these steps, you can help prevent these negative effects from happening:Limit coffee intake. The US Department of Health and Human Services states that you should consume no more than 2-4 cups of brewed coffee, or approximately, 400 mg per day.Avoid coffee beverages that are high in sugar. Doing so will help keep glucose levels steady and prevent crashes later in the day.Drink lots of water along with coffee. You can try alternating one cup of coffee with one cup of water. Watch for any signs of dehydration, such as cramps, thirst, or a dry mouth.Avoid the afternoon crash. Switch to a drink with less caffeine in the afternoon. Tea makes a good choice.Choose well-sourced coffee beans whenever possible. This will lessen your chances of coming in contact with harmful mycotoxins.Listen to your body and make adjustments as needed. If you notice any unpleasant sensations after drinking coffee, try cutting back to see if it helps.FAQsCan caffeine make me tired?Yes, it is possible, and even somewhat common, for caffeine to cause feelings of sleepiness versus the desired alertness and energy. This could be a result of dehydration, chemicals in the coffee, a sugar crash, adenosine receptors being blocked, or a high caffeine tolerance.Does coffee affect sleep?Coffee can be very disruptive to sleep. Most often, we see it causing difficulty falling asleep and/or reduced sleep quality. Even after coffee’s noticeable energizing effects wear off, the caffeine from it will continue to linger in the body.If you suspect that your coffee consumption may be interfering with your ability to sleep, you may want to try decreasing the amount that you drink on a daily basis and stopping caffeine intake earlier in the day to see if it helps.What happens to your body when you stop drinking coffee?This will be very personal to each individual. Some may experience uncomfortable caffeine withdrawal symptoms such as headaches, weight changes, dizziness, anxiety, irritability, mood swings, sluggishness, insomnia, and even flu-like symptoms at times. These should last two days to a week at most but if you feel any troublesome symptoms, talk to your healthcare provider.However, once this phase passes and the body adjusts to its new normal, better sleep is often reported. Quitting coffee may also help to lower blood pressure which can be temporarily elevated due to caffeine intake.How long until caffeine is completely out of your system?The length of time that caffeine remains in the body will be different for everyone. Each person’s metabolism is unique, as is the speed at which their body processes and breaks down caffeine. Factors such as age, body weight, and individual sensitivity can also affect how long it stays in the system.In the average adult, it takes between 10-12 hours to completely eliminate caffeine from the system.Pregnant women are one exception to this—they metabolize it much more slowly. According to a study conducted in 2017, caffeine can stay in a pregnant woman’s body up to 16 hours longer than usual.How soon do you feel the effects of coffee?Coffee affects the body very quickly; people will usually notice the effects within 10 minutes of consumption. The heart rate and blood pressure will begin to increase at this time.By the 30- to the 60-minute mark, coffee absorption is at the peak level. This is the point at which most of the caffeine in the drink has reached the body’s bloodstream. It is typically during this period that the effects will be strongest.ConclusionIf you’ve ever felt sluggish or drowsy after drinking a morning cup of coffee, one of these scenarios may apply to you. The way that coffee affects your body may leave you feeling tired due to dehydration, a sugar crash, blocked adenosine, high caffeine tolerance, and/or toxic chemicals.Thankfully, there are ways to combat these effects and prevent them from happening. By following the 2 to 4 cups per day guideline and drinking plenty of water in combination with your coffee, you should be able to minimize sleepiness and begin reaping its energizing benefits once again.About the author Jasmin LeeJasmin Lee is dedicated to helping others get better sleep—when she’s not napping, you can often find her researching the latest in bedding and mattress technology. Her fascination with sleep fuels her drive to connect readers with the resources they need to improve their night’s rest. Find more articles by Jasmin CommentsLeave a comment Nienna September 22, 2020 at 11:13 pm ReplyI sometimes drink a half cup at night if I can’t sleep. It numbs my anxiety so it can calm me down and I can finally sleep Daphney Small September 24, 2020 at 1:52 am ReplyBetter watch out cause Coffee will be the next ‘Killer Food’…LET THEM TELL IT!🤷 Leave a comment Cancel replyLeave a CommentYour email address will not be published. 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