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How does Coffee affect sleep?

Updated: Mar 30

Milk being poured into coffee, an image that justifies the article title of "How does coffee affect sleep"


Do you remember grabbing that cup of coffee while pulling an all-nighter before your last semester exam? We all have been there. In all honesty, the only way many of us made it through the college semester exams was by relying on a cup of coffee almost every single day.

Caffeine is the main ingredient in coffee which is responsible for causing instant alertness as it peaks in the blood within an hour of consumption. Caffeine primarily works as a central nervous system stimulant. It gives you that jolt of energizing freshness in the morning before you head off to work or college.

Many people rely on coffee to get that extra dash of alertness when they're sleepy. Coffee affects sleep, but how exactly does it affect our body and long-term sleeping habits? Let's find out.

How Caffeine Affects the Body?

Before we delve into how caffeine affects our bodies, let's take a brief look at how exactly caffeine functions at the physiological level. I was reading this book called 'Why We Sleep: Unlocking the Power of Sleep and Dreams' by Matthew Walker, Neuroscientist, wherein he beautifully explained caffeine's mechanism of action. Let’s take a deeper look at the key points from the thesis.

How Coffee Works: Caffeine's Mechanism of Action

Adenosine is a molecule derived from ATP, aka the 'energy currency of the cell.' This adenosine binds to specific receptors in the brain, leading to drowsiness. So the more adenosine build-up in your body, the more drowsy you feel.

If it's getting too technical, this will make it easier to understand. You must have noticed that when you wake up, you feel fresh and ready to take over the world, but by the time it is bedtime, you feel tired and sleepy. That is because adenosine levels are minimal when you wake up in the morning. As you go about your day, the adenosine starts accumulating in your bloodstream and binds to the receptors in the brain, signaling you to unwind and get a good night's rest.

Now what caffeine does is it fights with adenosine for the same adenosine receptor and blocks them, rendering these receptor sites unavailable. It basically makes you feel alert and awake by blocking the sleepiness signal, which is typically communicated through the adenosine molecule.

Health Benefits of Drinking Coffee

Caffeine is a popularly consumed beverage known for kicking in alertness; however, its effects are not limited to just that. It can benefit you in several other ways like:

  • Caffeine Improves Concentration

Researchers say that caffeine can improve your concentration. It causes the production of dopamine, which is a neurochemical responsible for controlling the ability to focus and maintain concentration.

  • Caffeine Enhances Memory

Coffee shows long-term effects on mental functions. Many studies suggest that caffeine improves cognitive performance.

Caffeine Improves Physical Performance

You must've noticed that many gym-goers consume coffee as a pre-workout drink. That's because of the rise in metabolism that follows coffee intake. It has been shown to improve your physical performance. Now you know what you got to do if you want to hit that extra set or push yourself in the gym.

These are some of the many benefits that caffeine potentially offers. A recent study suggests that drinking eight or more cups of coffee, caffeinated or non-caffeinated, can actually help increase your longevity which is astonishing. It implies that the non-caffeine constituents in coffee probably play an important role in this association, thus making it plausible to incorporate coffee into a healthy diet.

Several studies also demonstrate the use of caffeine in preventing and managing some chronic illnesses like Alzheimer's and Parkinson's disease.

How does Caffeine Affect Sleep?

Caffeine has a mean half-life of 5 hours.) (half-life means it'll take five hours for caffeine to reduce to half of its concentration), but it can stay in your body for up to 9-12 hours. That means one cup of coffee in the morning can get you through the most crucial part of your day when you need the maximum push. This can be different for different people. Some might require two or even three cups of coffee to get started. But do remember that the more coffee you consume, the longer it will stay in your body.

Coffee and Circadian Rhythm

Have you ever experienced a phase where you can't stop tossing and turning on your bed while attempting to get some shut-eye? If you're someone who consumes too much coffee or drinks it at the wrong time of the day, you must have experienced insomnia at least once in your life. It is the most common downside of consuming too much caffeine.

Our bodies follow a natural circadian rhythm which is responsible for maintaining the normal sleep-wake cycle. Consuming caffeine close to bedtime can throw you off this natural rhythm by causing insomnia. Studies have shown that chronic consumption of caffeine can also lengthen your normal circadian rhythm.

What is the Best Time to Consume Coffee?

Devouring a big cup of latte in the morning would be the best time for you to get that much-required dose of caffeine. Most experts recommend not having coffee after 2-3 pm if you start unwinding around 9 pm. It is best to avoid caffeine consumption at least 6 hours before bedtime to maintain your sleep hygiene.

Effects of Caffeine as you Age

If you live with your grandparents, you probably know they are light sleepers. That's because your sleep becomes fragile as you age, and your sensitivity to psychostimulants increases.

Studies suggest that older adults are more sensitive to caffeine. It deteriorates their sleep quantity as well as quality. This is probably because older adults consume the same amount of coffee as young adults despite weighing comparatively less, necessitating a smaller dose of caffeine.

How much Coffee is too much?

Caffeine has numerous health benefits when consumed in the right amount, but this right amount varies for every individual. We're all different, and so is our threshold for consuming caffeine. While the exact quantity of caffeine is hard to recommend, scientists say that you should not consume more than six cups of coffee in a day.

Not everything about caffeine is rosy. While caffeine in the correct quantity gives you the right amount of energy, too much coffee can cause

  • Restlessness

  • Insomnia

  • Headache

  • Fast Heart Rate

  • Dehydration

  • Anxiety

  • Dependence (addiction)

Scientists also say that too much of it can actually result in poor concentration and performance. Excess coffee consumption can even increase your risk of cardiovascular diseases.

Wrapping Up: How Coffee Affects Sleep

Coffee has the power to flip your day around. However, too much caffeine will most likely disrupt your sleep hygiene and make you an insomniac. It all comes down to your genetics and individual tolerance level. It is best to stick to the recommended caffeine intake mentioned earlier in this write-up.

For avid coffee drinkers who just cannot restrict themselves to six cups of coffee per day, just hold on until researchers find out whether coffee has an inverse effect on longevity. With so many advancements made in medical sciences, you will find it out very soon.

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