Skip to main content
Snooze Feed

Caffeine and Sleep: How It Can Affect Your Sleep

Does caffeine affect sleep? Of course it does! Anyone who tells you otherwise is selling something. But what they won’t tell you is that sleep and caffeine can get along just fine and can even work together for maximum productivity. In contrast, caffeine can wreak havoc on your circadian rhythm, and ultimately make you more tired day by day. It’s all about finding a healthy balance in what might be one of your closest relationships.

Coffee beans in line, slightly scattered.

Caffeine and Sleep: Frienemies Forever

If you rely too heavily on caffeine in any of its forms — be it coffee, energy drinks, tablets, etc. — your body could be sending you a very important message: less caffeine, more (or better) sleep. As obvious as it may seem now, it’s easy to drown that message with one more cup of coffee.

Tired, cranky man with cup of black coffee.

According to a study done by the Department of Phychonomics in the University of Amsterdam, caffeine can be “beneficial in restoring low levels of wakefulness” but may also “produce detrimental effects on subsequent sleep, resulting in daytime sleepiness.” One or a few cups early in the day can really help get you going, especially right after you wake up. An excessive amount or any too late in the day is what’s really going to create REM chaos.

The Sleep Foundation classifies six or more 8-ounce cups of coffee as excessive intake, whereas three 8-ounce cups of coffee is considered moderate. And since coffee can stay in your system for at least six hours, it’s generally a good idea to cut it out of your day after 2pm or so. So have no fear — you don’t need to break up with coffee, you just need to set a few boundaries so you and sleep can really work on making your relationship healthier.

Coffee Naps

Now for the good news! Coffee Naps are a thing. The forces of your two favorite pick-me-ups combined are much more effective than either one on its own. It basically all comes down to timing and chemistry.

The Science of the Coffee Nap

The Equation: Power Nap + Caffeine = Alert Bliss

Power Nap
As your brain works throughout the day, it produces a molecule called adenosine, which makes you feel more tired. When you take a 15-20 minute power nap those molecules dissipate, clearing your brain’s receptors and leaving you more alert.

Typically, most of the caffeine that affects you enters your bloodstream through the stomach and the small intestine. It usually takes about 15-20 minutes to really start kicking in.

Alert Bliss
Since the power nap is clearing your brain’s receptors of adenosine, the caffeine you downed right before your nap can fill in those gaps — not only without having to compete with the adenosine, but effectively blocking more adenosine from building up in the receptors for a while longer as you keep working.

The Art of the Coffee Nap

The ultimate key to the best coffee nap is timing. First, you’ll want to drink your caffeine quickly so you can get to your nap before the caffeine starts to kick in. Opt for an amount or temperature that you can consume relatively quickly. If you wait too long to nap, you’ll miss the amazing buzz of energy your coffee nap just created!

Second, it’s important to set an alarm that will get you up and functioning again in 20 minutes. If you oversleep, your body could start falling into deeper levels of sleep, causing sleep inertia and making you even groggier than you were in the first place.

If you didn’t sleep the whole time, or even at all, that’s okay. Resting quietly, eyes closed, can prove just effective. So drink up, set an alarm, respect the alarm, and enjoy!

Student in hoodie sleeping at desk with stacks of books and cups of coffee

Why Does Caffeine Make Me Tired?  

It may sound counterintuitive, but sometimes caffeine can actually make you feel more tired. If this sounds familiar, you’re not alone. 

There are a few different reasons this might happen to you, and it all has to do with the way caffeine affects the different systems in your body. 

Caffeine and the Central Nervous System

The main reason you may feel sleepy after downing a cup of joe is because of the way caffeine interacts with the central nervous system. It all comes back to that molecule adenosine we mentioned earlier. 

Caffeine blocks your brain’s response to adenosine, but that’s all it does. It doesn’t stop the body from producing it, just keeps you from feeling its effects. This means that as soon as the caffeine wears off, your body has built up its adenosine reserves. As soon as those reserves start binding to your brain receptors again, you start to feel sleepy. 

Caffeine is a Diuretic 

Caffeine is a diuretic, which means that it makes you have to pee more. Whenever your body is expelling extra liquids, you need to replace them or else you get dehydrated. 

Dehydration can lead to feelings of tiredness because your body doesn’t have enough fluid to maintain its blood pressure and blood flow. This not only leads to fatigue, but it can also lead to more serious problems such as rapid heart rate and low blood pressure. 

It may be tempting to reach for another cup of coffee to perk you up, but that just starts the cycle all over again. Instead, try drinking a large glass of water. It may not give you the rush of energy you’re craving, but it will make you feel less tired. 

Caffeine Narrows Your Blood Vessels 

Caffeine consumption could cause your blood vessels to narrow. This interrupts blood flow and makes it harder for your body to deliver oxygen and nutrients to the various systems throughout your body. 

Don’t worry though, it’s only a temporary response. Again, upping your water intake should help restore blood flow and counteract those feelings of fatigue and tiredness. 

It’s Not the Caffeine, It’s the Sugar 

Your depleted energy levels may not be because of caffeine at all. It may actually be the result of a sugar crash. 

Think about it: most of our favorite caffeinated beverages are loaded with sugar. Your average Starbucks coffee drink has around 50 grams of sugar in it, and energy drinks have around 30 grams. 

Your body processes sugar much faster than caffeine, and after it’s been used, you may experience what’s infamously known as a “sugar crash.” 

If this happens, the best way to recover is by eating a nutritious snack or meal that is high in protein and fiber. This will help stabilize your blood sugar and should hopefully restore some of your energy levels.

Listen to Your Heart

Caffeine can be your best friend or your worst enemy when it comes to getting the best sleep. Use it to get your juices flowing and to combat the 2 p.m. slump. But make sure to listen to what your body is telling you!

If you get jittery or have an elevated heart rate, you might be drinking too much. Other effects of too much coffee could also cause heartburn, mood swings, increased blood pressure, bone loss, and a whole slew of other scary problems. But for the most part, if you respect certain boundaries with caffeine, you’ll be just fine.

If you find yourself relying on caffeine more and more to get through the day, it might be time to look at your relationship with sleep (quality, quantity, schedule…all of it). Now go take a Coffee Nap!

Hands around cup of coffee with a heart drawn in the foam.