According to an article published on in the year 2009, coffee is drunk by around ½ of the American population every day with each person drinking on average 3-4 cups. Bennet Weinberg, who has written two books on the beverage, says that it is popular due to the kick it produces. Caffeine present in coffee stimulates the central nervous system; however, too much of it can actually decrease energy levels. This is why you probably have the question "why coffee makes me sleepy?"

How Does Coffee Help You Get Rid of Sleeping?

Caffeine stimulates the central nervous system and causes an increase in alertness and energy. It also boosts mood temporarily. However, it isn’t the stimulant that you think. Instead, it is the opposite. Throughout the day, the neuron produces a neurochemical referred to as adenosine into your body. Special receptors of the nervous system are used to monitor the levels of the adenosine. As the day passes by, increased amounts of adenosine reaches those receptors and the result is that your feel sleepy and tired at night.

Caffeine has the size and shape of adenosine and when they reach your brain, the adenosine receptors are unable to make difference. Due to the attachment of caffeine to the adenosine receptors, most of the adenosine molecules can’t attach to them. This helps you in keeping alert and awake as all the adenosine molecules are blocked. Caffeine also causes the activation of the sympathetic nerves, keeping you awake and alert.

Why Does Coffee Make You Sleepy?

However, the effect of coffee wears off after a short time, making you crave for one more cup of coffee. Coffee is a diuretic and the more coffee you drink, the more you will urinate. The increased frequency of urination will decrease the water in your system. Decreased water in the system makes your blood flow slow and you will feel even more tired than you are before. Hence, drinking coffee to stay alert and awake creates a vicious cycle that is very difficult to succeed. Drinking more and more coffee tires the nervous system and the sympathetic nerves become numb to the effects of caffeine. During this stage, you will not get that boost of energy, instead, you will have increased urge to visit the bathroom and feel more tired and sleepy.

Besides, when 4 cups of coffee block half of the adenosine receptors of the brain, the adenosine gets accumulated in the body. When the effect of caffeine wears off, the accumulated adenosine rushes to these receptors, which will make you feel more tired and groggier than before.

What Are Other Side Effects of Coffee?

Adrenal Overload

According to a report published in the July-August 2002 issue of Psychosomatic Medicine, drinking coffee all through the day can cause fluctuations in the levels of alertness and energy. Stephen Cherniske explains in the book Caffeine Blues that the effect of caffeine in the body is increasing the firing of the neurons in the brain. This increased activity of the neurons triggers the secretion of adrenalin hormone by the adrenal glands. Your energy levels are increased as the level of adrenalin rises. The repetition of this process in a day keeps your body in a constant state of “caffeinism.” The symptoms of this phenomenon include being anxious, feeling irritated, tired and depressed. 


Coffee is often considered to be harmless; however, it is a highly addictive drug that can induce anxiety. It not only increases alertness, but also increases nervousness and jitteriness. People suffering from anxiety disorder should completely avoid coffee. You can substitute coffee with herbal to feel in control of yourself.

How Much Coffee Can You Drink Every Day?

So, how much coffee you can drink? A study done in the year 2008 demonstrated that too much intake of caffeine is associated with low birth weight. Hence, it is advised that pregnant females should limit their consumption of caffeine to 200 mg per day (about 2 cups of coffee). People suffering from high blood pressure should avoid caffeine. However, in the UK there are no official guidelines regarding the consumption of caffeine. According to diet experts, caffeine consumption should be limited to no more than 4-5 cups of caffeine-containing drinks per day. Moreover, the last one should be in the afternoon as caffeine takes about 1 hour to kick in and its effects can remain for 5-6 hours. The good news is that you can take a cup of coffee in the morning to get your day started.

What Can You Do If You Want to Stay Awake?

Change the Temperature

Mental fatigue can be aggravated by stuffy and warm environments. To stay awake in a meeting room by lowering the temperature.

Use Cold Water

Use cold water to splash on your face and your wrists. You can also drink a glass full of ice cold water to keep awake.

Laugh a While.

Watch a funny video or read a funny comic. Laughing will stimulate your mind and help in keeping you awake.

Eat Smart

Eat a healthy and well-balanced meal and drink plenty of water. Eat regular meals that full of fresh fruits and vegetables.

Distract Yourself

Distract yourself by talking with neighbors or spending some time of Facebook. Unwinding or relaxing for a small duration can be beneficial and keep you more awake than your regular shot of caffeine.


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  • MarinaOct.13 05:57
    Both my father and I can drink cup of coffee and go to bed immediately. Coffee ha never help me to stay alert. The only "exception" if I mix coffee and alcohol - I am very sleepy but can't fall asleep. Never could figure out why.
  • Kathy VaalerJul.6 19:45
    After waking this morning from a good nights sleep, I had my one cup of coffee (half tsp creamer). I literally am fighting to keep my eyes open! I'm not Tired...I am Sleepy. Just started about a yr ago. Everyone says stop drinking coffee! That's not the point...WHY is it immediate???
  • SandyApr.7 15:43
    This is a very old thread but I found it on a search because coffee does the same thing to me! Within 15 minutes of an unsweetend cup of morning coffee I can't hold my eyes open even if I was perfectly alright and awake before I drank it.
  • MichaelDec.26 17:17
    Kate, Is this still happening to you? I'm going through the same thing, and I'm usually pretty sensitive to the effects of caffeine. This morning I had an unsweetened iced tea followed by two cups of coffee, and can barely keep my eyes open.
  • KateOct.25 17:55
    For the past few months, I have been unable to fight the "need" to take a nap, "immediately" following my usual one cup of morning coffee... Does anyone know why it's knocking me out? When for many years, it was my wake up, begin my day, go to!!! Now, I can literally not keep my eyes open before I've even finished my one cup of morning coffee!!! And even over the many years, I very rarely have a second cup, and if I do it's in the evening following dinner....(not anymore).
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