We all know that caffeine is a stimulant that we’ve come to rely on for a little boost. So why is it that your double shot espresso sometimes has no effect and in some cases, even makes you feel sleepy? Before stockpiling on energy drinks, read on to find out why caffeine can also make you feel tired. And more importantly, if caffeine has stopped having its desired effect, how to get that much needed boost back.

In this article, we’ll cover: 

How caffeine works on the human body

Adenosine, a sleep-inducing chemical produced by our nervous system, helps regulate our sleep. Adenosine levels increase during the day and prepare you for sleep at night by slowing down neuron activity. When we sleep, adenosine levels drop, leaving you feeling awake in the morning.

Caffeine works by blocking adenosine receptors, which prevents the brain from feeling the sleep-inducing effects of adenosine. The brain is so to speak tricked into keeping up neuron activity. This makes us stay alert and awake.

So why does caffeine make you sleepy?

There are multiple reasons why you’re sometimes left feeling sluggish when your favorite brew is supposed to do the opposite. You’ve likely landed in a vicious cycle of sleep deprivation and caffeine dependency leading to caffeine overconsumption and ‘immunity’. How?

1. Adenosine buildup

Caffeine prevents the brain from processing adenosine, but not from producing it. The greater the caffeine intake, the more adenosine is produced. Eventually, when the caffeine wears off, you’re left with an adenosine buildup that makes you feel even more tired. Hence the feeling of crashing and the need for an energy boost.

2. You don’t get enough sleep.

Remember the adenosine buildup? You need long, deep sleep to reset the adenosine levels in your body.  If you struggle to feel awake in the morning it could be because adenosine levels are too high. Your brain is simply still dialing down the neuron activity thinking you don’t need that brain power just yet. As a solution, you up the caffeine intake to cope with the sleepiness. We all do. But here’s the catch. Research shows that higher doses of caffeine are linked to poor sleep quality and insomnia. Caffeine interferes with the circadian clock, delaying the onset of sleep and preventing the much needed deep sleep. So with the increase in caffeine consumption, sleep deprivation eventually catches up. 

3. You have become immune to caffeine

Do you find yourself going through an increased number of tea bags every day, but without feeling any more awake? You might have built up a mild tolerance to caffeine. Remember caffeine is in many products. Tea, coffee, energy drinks, chocolate, sodas, even some medications all contain caffeine. In the course of a day, it all adds up. 

4. Caffeine withdrawal

For regular caffeine consumers, sleepiness in the morning can also be a symptom of abstinence. Your body is having caffeine withdrawal symptoms after having gone all night without it. Other symptoms of caffeine withdrawal are headaches, muscle pain, irritability, nausea and difficulty concentrating. The craving for another coffee or soda to make the symptoms disappear sets off the dependency cycle all over again. 

5. You’re dehydrated

We lose water while we sleep and often wake up dehydrated, especially if we don’t drink enough water throughout the day. Caffeine can cause further dehydration because it’s a diuretic, just like alcohol. Even small amounts make you frequent the bathroom more and cause you to feel tired and dizzy.

6. Timing is everything 

It takes about 15 minutes for your morning coffee to kick in. Caffeine levels peak after about 1 hour and stay there for several hours for most people. The duration of caffeine’s effect on our body is referred to as its ‘half-life’. What this means, is that 4-6 hours later, half of that morning coffee is still affecting your brain. It can take up to 10-12 hours to completely metabolize – or clear – caffeine from your bloodstream, so watch the afternoon pick-me-up’ers.

7. Watch the sugar 

Do you prefer your coffee or tea white, sweet, whipped and what not? Or do you have a craving for energy drinks? The added sugar in your energy drink or coffee creamer might be the real culprit. When the sugar wears off, blood sugar levels suddenly drop and cause that feeling of crashing we all know too well. 

What is the right amount of caffeine?

Your DNA determines how quickly you break down caffeine and how sensitive you are to it. The recommended amount of caffeine each day for an average person is 400 mg or 3 cups of coffee. Health experts agree that 4-7 cups of coffee which is 600 mg of caffeine a day is too much. You may not think you are getting too much caffeine, especially if you have built up a tolerance for it (remember #3?). But don’t mistake having “the jitters” or a racing heart for an energy boost. Other symptoms to be on the lookout for are: 

  • headache 
  • anxiety
  • dizziness
  • insomnia 
  • disrupted sleep
  • increase in blood pressure  
  • dehydration. 

If you feel any of these symptoms on a regular basis, it might be time to dial down your caffeine intake.

If caffeine makes me sleepy, can I then use it as a sleep aid?

The short answer? No. Caffeine is a stimulant that affects your sleep if consumed in excess or late in the day. Even if you have no problems falling or staying asleep at night, caffeine hinders restorative deep sleep which impacts your cognitive and physical health over time. 

6 ways to get your caffeine boost back

1. Wean yourself slowly

Cut back slowly and remember to avoid caffeine 6 hours as a minimum before bedtime. If you go ‘cold turkey’, you’re likely to experience the withdrawal symptoms mentioned earlier. This will only make you go back to your favorite caffeinated drink to make the symptoms go away. The more caffeine you’re used to consuming, the more severe your withdrawal symptoms will be and the longer it will take to wean yourself. After weaning yourself, you can reintroduce caffeine in moderate amounts.

2. Switch to decaf

If giving up your coffee or tea is a no-go, then gradually replace some of your daily brews with decaf or green tea. Both contain caffeine in significantly smaller amounts

Research shows that coffee drinking is more of a habit than a compulsive addiction and that we are responsive to caffeine cues (such as seeing and smelling coffee). So drinking decaf coffee can still curb the cravings, and elevate your energy levels and your feeling of alertness through a placebo effect. (Although being aware that it’s decaf might lessen the effects somewhat. )

Health experts even recommend coffee itself due to its high levels of antioxidants. (Phew!)

3. Get more sleep. 

If you’ve come to rely on a mid-afternoon caffeine boost to make it through the day, consider if going to bed a little earlier might do the trick. Remember, relying on that caffeine boost might just send you straight into a never-ending dependency cycle again. 

If you suspect insomnia (and you have dialed back on caffeine and the timing of it) you can also try melatonin as a supplement. It can help regulate sleep by preparing your body for bedtime. Always discuss these options with your physician. 

4. Take a power nap

Replace the midafternoon brew with a power nap. The urge to nap midafternoon is in fact a natural part of your circadian rhythm. More and more workplaces allow for a 20-minute snooze. Be aware, however, that stretching the nap past 20 minutes might affect your ability to sleep later, so remember to set your Sleep Cycle’s alarm.

5. Get your heart pumping in daylight

A brisk walk or afternoon workout helps you feel more energized and improves your cognitive performance and decision making.  A study even found that exercising between 1-4 pm can help you fall asleep earlier and easier at night. Also, try to take your work breaks outside. Getting outside during daylight will boost your vitamin-D production, making you focus and feel more alert while improving your sleep patterns. If you worry that your job doesn’t allow for afternoon walks or daylight exposure, try jumping jacks in the office and a lightbox. A little will do the trick.

6. Drink water

Remember how caffeine causes dehydration? The midafternoon slump you’re feeling might be the lack of water you’re drinking. Try to replace your usual afternoon brew with a big glass of water to combat fatigue. The recommended daily amount is 8 glasses a day. If that seems too optimistic, set smaller goals. Start your day with a glass of water before drinking anything else. And have a glass of water with every cup of coffee or tea. Is water too dull? Try adding lemon, cucumber or try sugar-free sparkling water.

Keep track of your caffeine intake in your Sleep Cycle app

Caffeine is a powerful tool that helps us concentrate and feel awake. But regular use and too much of it can cause us to feel depleted and unwell. Use the sleep notes in your Sleep Cycle app to keep track of your caffeine habits. Studying your habits can help you decide if and where you need to make adjustments for a more energized day and a better night’s sleep.


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