We’ve all been there before,  you’re running on empty, you still have a ton of assignments to do, and it’s only 1pm.  On a Monday.   So you head to the nearest break room and grab an iced coffee or your favorite soft-drink and try to power through the rest of the afternoon.  But can the caffeine actually be making you more tired?  Here are 12 reasons why you may want to think twice before drinking that 5th cup of coffee:

1. It messes with your sleep schedule

We all need a certain amount of sleep per night, and this is based on our level of activity, our height and weight, age, and other factors like genetics or general health.  If we drink too much caffeine, our normal 10pm bedtime may go to 1am because we aren’t feeling tired or because we can’t fall asleep quickly.

2. When you do sleep, it’s less quality.

It could take you longer to get to sleep at night, as mentioned above, and when you do, it may not be that good of sleep.  Slow wave sleep is required for true rest, and our brain goes through several stages of sleep before a full cycle is complete.  Caffeine can affect the ability to finish a full sleep cycle effectively, and then we wake up feeling more tired than we did before we went to bed.

  3. It makes you dehydrated.

Caffeine is a diuretic, which makes you dehydrated.  What’s worse, is that not only does dehydration make you feel icky, but it can make you feel sleepy as well.  Because the feeling of being caffeinated distracts you from all of that, when it wears off, sometimes you can feel even more tired than before.  If you are going to drink caffeine make sure you keep your water levels up as well.

   4. Adenosine builds up.

Caffeine acts as an antagonist, and blocks adenosine receptors from receiving adenosine, which makes us sleepy, among other things.  Unfortunately, it doesn’t block the body from producing adenosine, only from receiving it, so as soon as the effects of the caffeine wear off, a buildup of adenosine can make us really tired really quickly.

   5. Crash from added sugar.

There’s also a crash from the sugar high we receive as a result of caffeinated drinks.  Let’s face it, most of us aren’t drinking caffeinated water, we’re drinking sugary sodas or caramel macchiatos with chocolate syrup and whipped cream on top.

  6. Your genetics may prevent you from breaking caffeine down correctly

There’s a gene called CYP1A2, that decides how our bodies break caffeine down.  Some of us are better at breaking caffeine down than others, and if you’re someone that has a weaker CYP1A2 gene, you may be doing even more damage to your body with extra caffeine levels.  You can take a nutrigenomics test to determine the level that certain diets affect your body and vice versa.

  7. You may develop a tolerance to caffeine.

Have you ever drank your normal medium coffee just to find that it didn’t do as much for you as the one last week?  So the next time, you try a large, and then an extra-large.  Just like any substances we put into our body, we can learn how to react to caffeine and develop a tolerance for it,  requiring us to ingest more of it the next time for more effect, which makes us feel even worse after the effects wear off.  It’s a horrible cycle.

8. It’s a vasoconstrictor.

Caffeine is a vasoconstrictor, which means it makes your veins smaller and increases your blood pressure.  This means that your body is having to work even harder to pump blood around and throughout your body, and this also means that you’ll be even more tired afterwards.

  9. It messes with your insulin levels.

Caffeine can have a negative effect on our insulin (the added sugar doesn’t help) and it makes insulin less sensitive.  This makes it less sensitive to detect sugars in our body which makes it harder for insulin to turn sugar into energy, which in turn makes us feel more lethargic.

10. It produces adrenaline.

Caffeine can produce adrenaline, which helps create the “fight or flight” response within our body.   This can make us feel more tired after the fight or flight response wears off, but more importantly, it can make for a false alarm, meaning that we’ll be less likely to be able to produce the same amount of adrenaline the next time we need it, which leads to fatigue.

  11. It affects the rest of your body, including your stomach.

If you’re drinking soft drinks or especially coffee, you can have an effect on the amount of hydrochloric and stomach acid created by your body.  This can long term lead to things like irritable bowel syndrome,  acid reflux, heartburn, and other such problems.  This can make you feel badly but can also make getting to sleep at night difficult, or sleeping through the night impossible.

12. It’s not a substitute for sleep.

Everyone has a moment where they try to pull an all-nighter or substitute caffeine for sleep but the truth is that has really horrible health consequences down the line.  The best is to make sure your sleep (and exercise) patterns continue, regardless of the amount of caffeine you’re taking.

The bottom line is to use caffeine responsibly.  If you don’t abuse caffeine, and limit your caffeine intake to 400 milligrams a day (according to the Mayo clinic) — that’s about 4 cups of coffee — then you should still have no problem sleeping like a baby!