How to drink caffeine strategically with the 5 Levels of Fatigue

Originally published January 13, 2017. Updated Sept 10, 2019.

During grad school, while working 2 jobs and researching full-time, I developed a system called the “5 Levels of Fatigue”.
It started out as a set of rules to help me consume caffeine more systematically – as I biochemist, I knew if I always picked the most potent drinks, caffeine wasn’t going to work on those days when I needed it the most.

Below, I’ll walk you through my system and how to use it to drink caffeine more strategically, MAXIMIZING caffeine’s benefits while MINIMIZING its side-effects.

For info on using the 5 Levels of Fatigue against boredom, burnout, and mental overwhelm, you’ll want to check out this page:
Click HERE

What’s the best energy drink? Everyone has their own preferences based on taste, but the scientific truth is “the best energy drink” depends on your body and your situation. Think of it this way:

An energy drink is like your favorite song: what gets YOU pumped up may do nothing for ME. A song that gets you up and moving on a Monday morning is probably not your go-to song to celebrate a Friday night.

Everyone is different, and different situations call for different solutions (that’s a beverage pun right there – in chemistry, a solution is a liquid mixture).

This is a picture of a card I made for a PhD student leaving my lab in grad school. To help her remember me, I drew a self-portrait. Big hair. Music. Caffeine.

I developed the 5 Levels of Fatigue in college and in grad school. I was juggling full-time studies with two part-time jobs. In addition to studying the science behind energy drinks, I was drinking them - a lot.

As a biochemistry major, I knew caffeine would stop working for me if my body got too used to it on a regular basis. Caffeine blocks adenosine, which prevents adenosine from sending you “YOU ARE GETTING SLEE-PY” signals. But after awhile your body realizes caffeine is blocking adenosine and MAKES MORE, so it takes MORE caffeine to feel the same energy boost.

Using the 5 Levels of Fatigue makes it less likely you'll develop caffeine dependence - it means you won't need more and more caffeine to feel awake.

Here's How It Works:

  • Every energy drink has a different amount of caffeine, juice, and sugar.
  • Some energy drinks are carbonated, some are not.
  • Carbonation, juice, and sugar content will all make one energy drink FEEL more powerful than another drink with the same amount of caffeine.

FATIGUE LEVEL 1: Dehydrated & Drowsy

At this level, you’re feeling a little drowsy, but not exhausted or overwhelmed.

SOLUTION = Do something Different. Go for a walk. Switch tasks. Take a 5 min break. Drink WATER. DO NOT drink any caffeine at this level.

Caffeine Informer Bai Antioxidant Infusion caffeine content

FATIGUE LEVEL 2: Too Tired

At this level, “I’m too tired” becomes the excuse for action. You’re not exhausted and not just bored or drowsy. You’re just a little bit off, a little sluggish, a little lethargic. You’re “too tired”.

SOLUTION = A LITTLE sluggish means A LITTLE caffeine. Look for caffeinated beverages with no more than 100 mg caffeine.

  • NON-carbonated beverages will provide a gentler boost because carbonation irritates the stomach lining so caffeine gets absorbed more quickly.
  • TEA-based beverages will also provide a gentler boost because L-Theanine has a calming effect.

FATIGUE LEVEL 3: Stressed & Struggling

At this level, you’re starting to feel overwhelmed. You’re trying to wake up but you’re really struggling to stay focused and engaged. A walk and a cup of tea aren’t going to cut it here, but it’s still not worst-case scenario “energy emergency” quite yet.

SOLUTION = Several scientific studies and international organizations say you should have no more than 200 mg caffeine at a time. So that’s what we’re looking for here.

  • HYBRIDS are the best option here – energy drink/coffee hybrids, energy drink/wannabe Gatorade drinks, caffeinated juice blends
  • Pick carbonated over non-carbonated for an extra boost if needed
  • Pick sugar-free or drinks where the only sugar comes from juice – save the full-sugar versions for those “energy emergencies” at Fatigue Level 4

FATIGUE LEVEL 4: Energy Emergency

At this level, we’re going to ignore health guidelines and go over that 200 mg caffeine per serving recommendation. This is an energy emergency. This is one step short of being a walking zombie. We’re talking just-trying-to-survive, counting-the-hours-before-I-can-go-home crisis.

SOLUTION = Choose a carbonated energy drink with more than 200 mg caffeine per can. You can also pick an energy shot because shots have higher caffeine mg per oz than energy drinks. Energy drinks with sugar will give you an extra boost though you may crash after a few hours so ONLY pick drinks with more than 10 grams sugar if you absolutely need that much more help.

FATIGUE LEVEL 5: Zombie

At this level, no amount of caffeine can save you. This is your absolute breaking point. This is worst-case-scenario.

SOLUTION = Only sleep can save you now.


This is the 5 Levels of Fatigue.

How Energy Drinks Affect Children and Young People: Research Recap

Energy drinks do not belong in the diet of a five-year-old. You already knew that. But do you know what happens when children do have energy drinks? Thanks to research by Durham University in the UK, we now have a good idea how many kids and teens in different countries drink energy drinks and how those drinks affect their health.

›We’re recapping the findings of this paper: “Consumption of energy drinks by children and young people: a rapid review examining evidence of physical effects and consumer attitude

*Note – the research paper by Durham University uses the expression “children and young people” to refer to those under 18. At the age of 33, I still consider myself a “young person”, so I’m going to use the expression “kids and teens” instead. Read more

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