How Does Caffeine Affect Your Sleep Cycles When Taken Before Bed?

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Caffeine is America’s most popular drug.

83% of Americans drink coffee daily. The average is three cups a day. That seems like a lot, doesn’t it?

It also seems that no matter where you turn, you’ll find conflicting information about whether coffee is a healthy, miracle drug packed with antioxidants or an acidic monster that does nothing but cause “adrenal fatigue.”

The truth, as is almost always the case, lies somewhere in the middle.

While it can be a powerful and harmless pick-me-up, caffeine does affect sleep. However, if taken with intention and at the right time each day, you can reap all of the benefits without harming your sleep.

In this article, we’ll dive deeper into the numerous benefits of caffeine, its risks, and guidelines on drinking it on a daily basis. We’ll also answer questions about how long it takes to feel the effects and how long caffeine’s energy boost lasts.

Can Caffeine Affect Sleep?

There’s no doubt that it affects sleep. However, the effects vary greatly, depending on the individual.

Caffeine disrupts sleep in the following ways:

  • Prolonged sleep latency (it takes longer to fall asleep)
  • Less time spent asleep overall
  • Waking up more frequently during the night
  • Less time spent in REM sleep

The factors that influence how much caffeine affects someone include:

  • Age (as we age sensitivity increases)
  • Sensitivity levels (some are more prone to the effects than others)
  • How regularly they consume it and how much they ingest
  • The time of day the consumption occurs
  • Genetic variability

Despite the undeniable benefits of caffeine, the fact that it’s known to have a negative impact on sleep gives us pause. Later in this article, we’ll share tips on how to still drink coffee without sacrificing sleep quality.

girl drinks coffee and looks at the laptop

Benefits of Caffeine

Increases Dopamine

Dopamine controls the brain’s reward and pleasure centers. People who are in love or on a winning gambling streak have ample amounts of the dopamine neurochemical in their brain. Caffeine increases dopamine production and can create a high that’s similar to that of amphetamines.

While this gives us a euphoric rush of energy, it’s this effect that also causes caffeine to be so addictive.

Lowers Risks for Heart Disease

Some studies suggest that caffeine consumption lowers the risk of heart disease by up to eighteen percent. The jury’s still technically out on this one, though. Researchers theorize that it may just be that coffee drinkers have healthier habits overall than non-coffee drinkers.

They also have failed to report why people who imbibe this brown morning elixir would also have healthier habits. Still, we’ll drink to that!

Lowers Risks of Stroke and Type 2 Diabetes

The Harvard School of Public Health found that drinking coffee reduces the risk of stroke and Type 2 diabetes. They believe that coffee’s antioxidants produce an anti-inflammatory effect. Further, coffee also contains minerals like magnesium, which is linked to lower rates of Type 2 diabetes.

Reduces Depression

We briefly mentioned that caffeine stimulates the production of dopamine, the pleasure chemical. It also boosts serotonin levels, which is widely known as the “happiness” chemical. In fact, anti-depressants use something called a serotonin reuptake inhibitor to make more of this chemical available in the brain.

If you’ve ever noticed that you feel more alive after drinking a cup of joe, you’re experiencing a natural anti-depressant.

happy woman is drinking coffee

Fights Neurodegenerative Diseases

Numerous studies have pointed to caffeine consumption reducing the risk of neurodegenerative diseases like Parkinson’s and Alzheimer’s. While researchers are still trying to find the exact reason, they have pointed out that coffee has a complex chemical makeup and could have more benefits than we even realize.

Burns Calories

In the short term, caffeine boosts metabolic processes and can raise your internal body temperature. The result is a thermogenic effect that puts your body in fat burning mode. However, it doesn’t take long for your body to adapt to this effect, so it’s not a long-term diet plan.

On a positive, caffeine does suppress the appetite, which can contribute to weight loss. Also, the energy boost that you get from drinking a cup or two might get you moving around, which also burns more calories.

And finally, coffee contains chromium, a mineral found in many over-the-counter weight loss supplements.

Reduces Muscle Pain

Some elite athletes drink coffee before a grueling workout. We always assumed that the increase in blood flow would help with circulation and therefore reduce pain, but the reality of the situation is much juicier. It turns out that there is a compound in coffee, that when isolated, has a similar but potentially more powerful effect than morphine.

Before you get too excited, note that a single cup of joe won’t have a dramatic effect, but it definitely helps.

If you’re getting ready for a cardio workout or an intense weightlifting session, you may want to try a small cup of coffee or tea first. It might make those hills easier to climb and lessen the burden of the heavy weights.

Improves Mental Performance

The alertness that comes along with caffeine consumption is known to improve mental performance. It’s reported to improve short-term memory and reaction times, as well as the ability to think quickly and “outside the box.” Need a creative boost for a solution to a complex problem? A steaming hot cup of black coffee might do the trick.

a cup of black coffee

Negative Effects

Blocks Adenosine

Buzzkill alert. For all the lovely and positive effects of caffeine, you knew there’d be a flipside, right? Unfortunately, this wonder drug blocks the body’s ability to produce adenosine. This is a chemical in our body’s that makes us sleepy. Its levels increase as the day goes on. When we drink coffee, it blocks our body from producing it, keeping us awake.

Over time, it can mess with your ability to self-regulate sleep cycles.

You’ve probably also heard of something called adrenal fatigue. This is caused by caffeine’s effect on the adrenals. The adrenal gland produces adrenaline and cortisol (a stress hormone). When you drink coffee, you’re signaling the pituitary gland to message the adrenals to produce more adrenaline and cortisol than you need for your typical day at the office.

If you drink coffee throughout the day, you’re keeping your body in an artificial state of fight-or-flight. Over time, this exhausts your nervous system, and you.

Suppresses Melatonin

Similar to adenosine, melatonin is a hormone that causes drowsiness. It also peaks at night and in darkness. Daylight and artificial light also suppress melatonin, but it’s been reported that caffeine does so even more aggressively.

We are firm believers that as long as you limit your intake to the morning hours, you won’t mess with melatonin production significantly.


A stimulant can stay in your body for hours. If you consume it within hours before bed, it’s only natural that it could potentially keep you awake.

Again, this stimulant affects everyone differently. You probably know someone (or you might even be that person) who can drink a metric ton of coffee and then go straight to bed and sleep peacefully all night.

Speaking of drinking coffee and then going straight to bed, have you heard of a coffee nap as a new form of power napping? It’s amazing.

Here’s how it works: if you’re feeling drowsy, drink a cup of joe (or strong tea) and then set an alarm to wake up in 20 minutes. You should fall asleep right away because the stimulant hasn’t entered your system yet.

When the alarm goes off 20 minutes from when you lie down, you’ll be feeling the effects of your energy boost, and you’ll wake up refreshed and ready for a second wind. We know it sounds strange, but don’t knock it ‘til you try it.

girl fell asleep at work

Headaches, Nervousness, and Dizziness

Everyone has different tolerances. Some people can consume this beverage all day long and have none of these ill effects, while others take merely a sip and develop a headache or feel anxious or dizzy. This happens in people where caffeine increases the heart rate. A higher heart rate can lead to one or all three of these symptoms.


Some people get the jitters when they consume caffeine. It’s similar to a fight-or-flight response and can cause anxiety in some cases. Keep an eye on this because the effects of mild anxiety can snowball, create an avalanche effect, and result in a full-blown panic attack.


For some, not having their morning cup of fuel can cause irritability. But for others, drinking it can make them impatient and irritable. This is because the release of adrenaline puts your body in a more alert state. Great for crunching numbers, but not so great if you get cut off in traffic or a coworker insists on showing you pictures of their cat. Again.

Caffeine Levels


The amount of caffeine in a cup of coffee can vary widely, depending on the type of bean and how the beverage is prepared. On average, expect to find about 100 milligrams of caffeine in an eight-ounce cup of joe. A shot of espresso has about 64 milligrams.

If you’re in the habit of getting Venti-sized beverages from Starbucks, triple that 100 mg calculation. Switching to decaf? There are still two milligrams, which we think is negligible, but should at least be noted.


Black tea has about half the caffeine of coffee. If you’re consuming green or oolong tea, expect about a third of the amount that coffee has. Herbal and white teas have zero to five milligrams. The exact amount will vary based on the brand, so check labels carefully if you’re sensitive.

Energy Drinks

There’s some variation here as well, mostly due to the size of the cans. Red Bull cans are just over 8 ounces, and the amount of caffeine in one of those beverages is slightly less than coffee (about 77 milligrams). The 12-ounce cans have 11 milligrams.

Larger cans like Monster and Rockstar contain between 158 and 173 milligrams in a 16-ounce container.

Red Bull energy drink


There are caffeine-free sodas, but most do contain some. In a 12-ounce can, you’ll find a range of 34 milligrams in Coca-Cola to 54 milligrams in Pepsi. Other brands like Mountain Dew and Mello Yellow fall somewhere in between.


We’re not talking about your cholesterol medication. Rather, we’re referring to gas station stimulants like No-Doz, Vivarin, and Excedrin. A single tablet of No-Doze or Vivarin has twice as much as a cup of coffee at 200 milligrams. Excedrin Extra Strength has 130 milligrams, making you wonder if there’s more to the effects of caffeine on pain than meets the eye.


Some foods contain caffeine. Chocolate is an obvious one that comes to mind. But you’d have to eat nearly half a pound of chocolate chips just to get the amount that’s in one cup of coffee.

Recommended Amount of Intake

Most adults can consume about 400 milligrams of caffeine safely and with no ill effects. This equates to about four cups of coffee per day. Keep in mind, those are eight-ounce cups. Most coffee mugs are 16 ounces, so we’re not saying that the FDA and other governing bodies recommend four of those. Rather, stick to two and so during the earlier part of the day.

If you’re experiencing health challenges or on medication for conditions like high blood pressure, you’d be wise to consult with your doctor about how much you’d be able to safely consume on a daily basis. Remember, we’re not medical professionals.

Guidelines for Intake

In addition to watching the amount you consume, we suggest the following guidelines:

  • If you’re pregnant or nursing, consider avoiding this stimulant. Some physicians say it’s okay to consume a cup a day, so again consult with your doctor. The myths about stunting growth have already been dispelled, but we still have concerns about the effect it has a stimulant and the potential for addiction.
  • If you’re a parent, monitor your child’s consumption carefully. In our day, kids didn’t drink coffee, but with a Starbucks on every corner these days it’s hard to keep our children away from coffee. If you allow them to indulge, we suggest no more than one cup a day, limited to the early morning hours.
  • If you have high blood pressure, heart problems or a serious health challenge, get the okay from your doctor before consuming.
  • Avoid caffeine before bed, and stop drinking it in the afternoon and evening. We suggest cutting off coffee by noon. If you’ve got an after-lunch lull and a walk outside isn’t enough to revive you, feel free to enjoy a post-meal coffee, but do so before two o’clock in the afternoon.
woman drops sugar in cup of coffee

Frequently Asked Questions

How long does it stay in your system?

We measure this in terms of half-life. Bear with us; we’ll handle all the math for you.

The half-life of caffeine is five to six hours. This means that it takes that amount of time for half of the chemical to leave your body. Generally, you’ll feel the effects of coffee strongly during that time. After the initial half-life period, it continues to dissipate at a varying rate. That’s why a cup of coffee at one in the afternoon can keep you up well past midnight.

How long does it take to kick in?

About 99% of the caffeine is in your bloodstream within 45 minutes of consumption. However, it begins to enter your bloodstream immediately after your first sip. This means you can start feeling the effects within a couple of minutes, but on average expect it to take about 15 minutes to feel more alert.

What is caffeine overdose?

An overdose is extremely rare. If you were to suffer from an overdose by drinking coffee alone, you’d have to consume about 30 cups of the stuff. When you hear about an overdose, it’s invariably due to someone taking a tablet of concentrated caffeine powder. If you’re tempted to try this, take it in small doses only.

How long does caffeine withdrawal last?

You’re not thinking of quitting, are you? The headaches alone should be enough to scare anyone off! Other symptoms of withdrawal include sleepiness (obviously), constipation, irritability, depression, brain fog, and more. The list goes on. It’s horrible.

If you’re a light coffee drinker, you might get off fairly easily and have symptoms for a few days to a week. But if you’ve been a habitual consumer for years, you might go through this torture for two months or more.

It’s not all negative, though. Even the heaviest coffee drinkers report that the worst of the symptoms subsided in about a week’s time.


You can probably tell that we’re biased toward caffeine. We love it, and we think it gets a bad rap that’s not at all deserved. From our perspective, we see a ton of the benefits with very little downside.

We believe that as long as you consume responsibly and in moderation, you’ll have a healthy and antioxidant-packed helper to get you through long days with grace and ease.


  1. Caffeine & Sleep Problems – National Sleep Foundation
  2. New Details on Caffeine’s Sleep-Disrupting Effects – Psychology Today

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Author: Sleep Advisor

Our team covers as many areas of expertise as we do time zones, but none of us started here as a so-called expert on sleep. What we do share is a willingness to ask questions (lots of them), seek experts, and dig deep into conventional wisdom to see if maybe there might be a better path towards healthy living. We apply what we learn not only to our company culture, but also how we deliver information to our over 12.7M readers.

Sleep research is changing all the time, and we are 100% dedicated to keeping up with breakthroughs and innovations. You live better if you sleep better. Whatever has brought you here, we wish you luck on your journey towards better rest.

The Sleep Advisor