Now that you know what caffeine does, let’s see why it sometimes appears to make people feel tired.

As it turns out, there are a number of possibilities.

Adenosine

Yep, here we are again, talking about adenosine.

You know that caffeine blocks the ability of adenosine to make us feel tired. But that adenosine doesn’t just give up and go home – it waits. In fact, the brain keeps producing it.

So when caffeine finally goes on its way, that build-up of adenosine attaches to the A1 receptors and can make you feel even more tired than you normally would. It’s similar to experiencing a sugar rush; the rush is almost always followed by a crash.

Speaking of Sugar…

It might seem that caffeine is making you tired, but what may really be hitting you is a sugar crash.

Many of us love our soda sweet, and our coffee loaded with sugar. Unfortunately, consuming lots of sugar – not to mention all of the yummy sweet stuff in coffee drinks – causes the body to produce higher levels of insulin.

In turn, the insulin causes blood sugar (glucose) levels to drop. And when blood sugar falls, we get tired, anxious and irritable.

Here’s what that means: we’re not necessarily sleepy because of the caffeine in caffeinated beverages. Our body is just crashing after an initial sugar rush. If you’ve had a Cinnabon or other sweet treat with your coffee, they can make the problem even worse.

One way to deal with the issue is to sweeten coffee with natural, non-nutritive sweeteners like monk fruit extract.

A good option is Super Coffee ready-to-drink keto-friendly coffee; it already contains monk fruit sweetener, as well as the MCT oil that helps keto dieters burn fat more efficiently while supplying extra energy.

Tolerance

The body can build a tolerance to almost any drug, and that includes caffeine. The more habituated you get to caffeine, the less of an effect it will have on your heart rate, your blood pressure, and importantly, your energy levels.

In other words, coffee won’t keep you awake in the same way it did before you started drinking a lot of it.

There’s an interesting twist, too. When you consume a large amount of caffeine each day and it regularly blocks the adenosine receptors, the brain responds by simply creating additional adenosine receptors. That can make it more and more difficult to get the same effect from coffee, tea, Coke or energy drinks.

How do you overcome caffeine tolerance? The best way is to completely eliminate it from your daily routine for a while.

Probably more reasonable for a coffee lover: reduce your caffeine consumption by switching from black coffee, espresso or other caffeinated beverages, to water, fruit juice or decaf (which only contains a fraction of the caffeine in coffee).

When you go back to your coffee or caffeinated soda, not only will the tolerance issue be eased – but you’ll appreciate the caffeine more than ever.

There’s a catch-22 to be aware of, though, and it’s one you may have experienced.

If you drink coffee regularly and then stop abruptly, you could suffer what’s known as caffeine withdrawal. Like any type of drug withdrawal, it can produce side effects like irritability, headache – and, you guessed it, fatigue. The issues can be avoided by cutting back gradually instead of going cold turkey.

Dehydration

One of the well-known effects of coffee is that can produce diuretic effects. That’s a polite way of saying it makes you pee more than usual. The effect really shows itself in heavy coffee drinkers once they go past three or four cups of coffee per day.

When you urinate a lot, you’re likely to be losing more fluid than you’re consuming – and that can make you dehydrated, which may cause dizziness, dry mouth and – yes - fatigue.

If it feels like caffeine is making you more tired than usual, try drinking more water than usual. Eating foods that contain lots of water, like vegetables and fruit, can help you get enough water into your body as well.

Or, of course, you could just reduce the amount of coffee you drink each day.

Stress

When you’re stressed or anxious, your body goes on high alert and releases the stress hormone cortisol and the “fight-or-flight” hormone epinephrine (better known as adrenaline). Those hormones cause the increase in heart rate and blood pressure that we’ve all experienced under stress.

Immediately after the stress or anxiety is relieved, you don’t just feel “better” – you’re also likely to feel more tired than usual.

Guess what drinking coffee and other caffeinated beverages does? It induces the body to produce more cortisol and adrenaline.

A study at The Ohio State University found that caffeine intake, from any source, doubles the body’s natural levels of the hormones. So a cup of joe or an energy drink may actually make your body feel stressed, and its natural reaction once the caffeine wears off is to feel tired. The effect is even more pronounced in those with pre-existing stress and anxiety issues.

Contaminants

Coffee beans are prone to growing mold – and mold often produces toxic compounds called mycotoxins.

In most cases, the level of mycotoxins in coffee is considered “safe.” But here’s the problem: mycotoxins can cause chronic fatigue.

You’re not going to do a lab analysis on your coffee before drinking it, needless to say. It’s smart, however, to make sure the coffee you drink is as fresh as possible; otherwise it might seem that caffeine is making you tired, when the culprit is really microfungi.

Caffeinated beverages can unquestionably deliver a quick jolt of energy. Coffee and tea, in particular, provide a number of health and wellness benefits as well.

But to ensure that your caffeine boost doesn’t wind up actually making tired, pay attention to the other factors that can negate the alertness and wakefulness you expect when pouring that morning cup of coffee.