It is widely known that caffeine combats sleepiness, to the extent that it is used in research to simulate insomnia, so it’s no wonder that a strong brew of tea or coffee in the morning is probably part of your daily habit. Ideally, you could manage your schedule around your natural sleep cycle but, since this is hard, caffeine is a common way to remain alert throughout the day (or maybe even the night!).
Caffeine has quite a few advantages. It’s widely accessible and consumed around the world. You can pop into a local cafe for coffee or tea, pick up a chocolate bar from the shops, get a cola or an energy drink from a vending machine or even get caffeine pills from the pharmacy.
Its effects kick in pretty quickly, usually within 30 minutes. The effects of caffeine include:
Some research suggests that people who drink more coffee are less likely to develop Alzheimer’s disease. But this research is still in its early stages and it is not recommended to consume caffeine as a way of preventing dementia - especially since it’s very easy to build up a tolerance to the caffeine, which means higher doses are necessary to have an effect.
It’s important to note caffeine has downsides, too: higher doses (around 500-600 milligrams a day) can cause jitteriness, heart palpitations and headaches. It can also worsen existing conditions like anxiety, high blood pressure and insomnia.
When it comes to dozing off, caffeine counteracts the way the brain prepares for sleep. Throughout the day, the need for sleep builds up, in part regulated by the naturally occurring chemical - adenosine. Levels of adenosine rise as sleep debt builds up - the longer you’re awake, the higher the level of adenosine in your system. Our brains register rising levels of adenosine as a sign of increased sleepiness. But when you consume caffeine, it interacts with adenosine by blocking its absorption – the brain doesn’t register that it feels sleepy, meaning you feel awake.
However, you can’t just keep drinking coffee and never sleep; over time, you’ll need more coffee to get the same effect, and the adenosine can’t be blocked forever. Once the effect of caffeine wears off, you’ll experience a crash where all of the adenosine that has built up is suddenly registered by the brain, and it will be even harder to not fall asleep. Similarly, routinely consuming caffeine to feel alert after short or restless sleep can become a vicious cycle, where sleep deprivation worsens, impacting your thinking, planning and overall brain function.
Cutting down on caffeine consumption can be hard – one way of improving sleep habits is trying to reduce consumption to smaller and more frequent amounts. The European Food Safety Agency (EFSA) recommends a maximum of 400 milligrams of caffeine for adults consumed during a day, with no more than 200 mg per dose. This differs if you’re pregnant or underage, where smaller doses are advised.
How late can you drink coffee without affecting your sleep negatively? This depends how quickly it’s processed in the body. Like with most consumable compounds, the speed at which caffeine takes effect on the body varies between individuals. On average, recent research shows that you should stop consuming caffeine about 6 hours before bed to make sure you sleep well.
Altogether, caffeine has its uses, and it’s advised to use it little and often, meaning you benefit from its effects without building up a tolerance, while still allowing you a night full of sleep.
Researched and written by Marta Strzyga