Caffeine and Sleep: How To Find The Balance

6 Min Read | By Lottie Salako

Last Modified 6 December 2023   First Added 23 November 2023

This article was written and reviewed in line with our editorial policy.

Humans have been enjoying the benefits of caffeine for thousands of years in the form of tea, coffee, and even chocolate. It was first isolated from coffee in 1819, and since then, it’s one of the most commonly consumed psychoactive drugs in the world!

With the modern world inundated with cosy coffee shops and celeb-endorsed energy drinks, caffeine is everywhere. It seems like everyone needs it and loves it. But, some of us may have noticed a correlation with poor sleep that leaves us even more dependent on our daily pick-me-up. So, what are the real impacts of our favourite stimulant?

Why does caffeine energise you?

Caffeine is a naturally occurring chemical that acts as a central nervous system stimulant. This means it affects our brain and spinal cord, as well as the messages they send to the rest of the body. The most common effects include increases in energy metabolism, blood pressure, and dopamine release. All of these add up to that burst of activity and focus we get after that oh-so-satisfying sip.

How does it affect your sleep?

Unsurprisingly, something that makes us feel more awake can have a negative impact on our quality of sleep. There have been many studies into caffeine and sleep, trying to understand how the stimulant affects rest and if there are other reasons for the correlation we see between caffeine consumption and bad sleep.

One interesting study used a community living in rural Ecuador to mitigate other disturbances, such as noise and light pollution. The researchers found that caffeine had no negative impact on their sleep, indicating that it doesn’t keep you awake but makes you more sensitive to wakefulness.

The results were adjusted for differences in lifestyle, however, many other studies found a correlation between caffeine consumption and poor-quality sleep. Some show that coffee increases how long it takes to fall asleep and how well you sleep.

Frustratingly, there are many factors to consider. One of which is the “coffee cycle” – this is when people who are already sleep deprived try to combat their exhaustion with coffee, leading to more bad sleep and a dependency on caffeine to get them through the day.

If you find yourself in a place of not sleeping at night and being exhausted all day, then it’s time to reassess your sleep hygiene and habits. Sleep deprivation can have serious health implications, so we recommend visiting your GP to discuss possible causes and fixes.

A white and red mug on a wooden table, half-filled with black coffee. The words "NEED MORE COFFEE" are printed on the mug. A white and red mug on a wooden table, half-filled with black coffee. The words "NEED MORE COFFEE" are printed on the mug.

Understanding how much caffeine you should have

Caffeine isn’t the fix-all to productivity issues. These same processes can also cause anxiety, restlessness, and difficulty focusing as they stimulate our flight or fight response. In some rare cases, caffeine overdoses can cause heart problems, so it’s important to be mindful of how much you’re having.

But how do you know how much caffeine is too much? There is strict guidance around the recommended amount to avoid toxicity:

  • Moderate daily caffeine intake at a dose level up to 400mg/day (for a 65kg person)
  • Women who are pregnant should consume no more than 200mg/day (for a 65kg person)
  • Children should consume no more than 45mg-100mg/day (although it is generally recommended children should have no caffeinated drinks)

But what do these numbers mean in terms of beverages? Let’s take a look:

Drink Average caffeine dosage
Brewed coffee 1 mug (200ml) 100mg caffeine
Instant coffee 1 mug (200ml) 60mg caffeine
Tea 1 mug (200ml) 45mg caffeine
Green tea 1 mug (200ml) 30-40mg caffeine
Can of cola (330ml) 35mg caffeine
Can of energy drink (250ml) 80mg caffeine
Small bar of chocolate (50g) 5-36mg caffeine

Which? did an investigation into caffeine levels across high street coffee shops that showed an interesting variation in dosage levels across different drinks:

However, we shouldn’t be scared of caffeine. Experts at Johns Hopkins state that there are more health benefits to a cup of coffee than we often think about.

Studies have shown that a moderate amount can reduce your chances of developing type 2 diabetes, heart failure, Parkinson’s, colon cancer, Alzheimer’s, and strokes. And perhaps surprisingly, you can even combine caffeine with a nap to supercharge your focus throughout the day. Let’s explore.

Does the nappuccino work?

This little trick is used by busy people like Paralympians to get more sleep and a midday caffeine kick! So, how do you do it?

  1. Drink a cup of coffee quickly – the best type for this would be espresso shots or a small cappuccino (the clue’s in the name!).
  2. Go for a power nap of 15-20 minutes maximum. This is roughly the time it takes for caffeine to peak in your bloodstream.
  3. Jump out of bed refreshed and ready to take on the day.

Does it actually work? Well, one nappuccino study says yes. Even if you only momentarily drift off, the pairing of caffeine and sleep can be really effective against late afternoon slumps.

This is because of a chemical called adenosine, which slows your heart rate. During sleep, your brain recycles adenosine, so that upon waking, you are more alert.

Caffeine also blocks adenosine, which is why it raises your heart rate and makes you feel awake. This creates a winning combination for combatting energy slumps.

If you usually feel groggy or have a hard time focusing after a nap, then this can also help with that. You’ll gradually feel the energising effects of the coffee, which should prevent drowsiness. Plus, a nappuccino calls for a very short sleep time, while naps over 30 minutes typically end with an interrupted sleep cycle, often the cause of lingering sleepiness.

Want to know the secret to power napping? Learn here...

Caffeine and ADHD

If you have ADHD, you may notice that caffeinated drinks don’t have the same effect on you. Because of how ADHD affects the brain chemistry and how it responds to stimulants, caffeine may not give you a boost of energy, but instead have a calming effect.

The recommended treatment for ADHD is stimulant medication because it is theorised that increased dopamine levels help to curb inattentiveness and hyperactivity. Therefore, coffee and energy drinks may help those with ADHD focus.

It is important to be aware of your own responses to caffeine. Some people are more sensitive to it, causing jitters, heart palpitations, anxiety, and an upset stomach, so it’s best to avoid or stick to a low dosage. Likewise, if you’re already on a stimulant medication, then you want to consult your doctor on how this may interact with caffeine.

A cup of tea sits on a wooden coaster, with a slice of cake and a flower vase in the background. A cup of tea sits on a wooden coaster, with a slice of cake and a flower vase in the background.

Alternative pick-me-ups for better sleep

Caffeine has a rather long half-life (the amount of time that it’s active in your system) of around 8-12 hours. For most people, this means that to avoid being kept up past bedtime, you want to only have a high dose of caffeine in the morning or early afternoon.

However, this may not be the best news if you’re someone who enjoys the taste or like to have a hot drink throughout the day. Here are some alternatives with less caffeine and more health benefits:

  • Hot cocoa
  • Warm milk
  • Chamomile tea
  • Decaffeinated green tea
  • Water

Learn more about why these are great for sleep in our posts on the best drinks to have before bed and herbal teas for better sleep.

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