How long do the benefits of caffeine last?

A cup of coffee sitting on a table

This week’s blog is about caffeine. I get asked quite a lot how long do the benefits of caffeine last in the blood stream, and that leads to a separate issue which is in some respects, how quickly can you eradicate caffeine from the bloodstream because we know it already has a knock on effect on sleep.

Whether it’s companies or individuals, I like talking about sleep and caffeine to try and educate people on just how long caffeine lasts in the bloodstream.

In Matthew Walker’s book, Why We Sleep (which I highly recommend), he said that caffeine has a quarter life of 12 hours. What this means is if you have a cup of coffee at 9:00 in the morning, you will be processing out the last of that caffeine at potentially midnight. It stays in the bloodstream a lot longer than people think. Some people are fast metabolizers of caffeine, some are slow metabolizers – this is something you can find out through DNA testing for example.

If you’re a slow metabolizer, it’s probably going to be 15 hours before you process it out. If you’re a fast metabolizer, it might be 12 hours. But that 9:00 cup of coffee in the morning is still in the bloodstream at 9:00 at night. Whilst caffeine is useful for cognitive enhancing performance – for example it’s used for athletes to enhance performance. I think caffeine 20 minutes prior to a race or a significant athletic event can have beneficial properties. But for some people, it’s not actually a good substance to consume in great quantities.

If you’re having any kind of energy or sleep issue, looking at your caffeine intake is a really good place to start. In my experience, most people are over consuming or over relying on caffeine. People commonly have caffeine in the morning to get pepped up, sugar in the middle of the day to keep pepped up and then alcohol potentially used to wind yourself down in the evening.

So start to have a think about your caffeine intake – you don’t need to go to the length of testing to see whether you were fast or slow metabolizer of caffeine, but just start to understand. When we think about stable energy and good sleep, caffeine is one of the key contributors to that.

If you can monitor your caffeine intake and start to reduce it, maybe go from three cups to two cups and change to decaffeinated, or three cups to two cups of coffee and one green tea. It’s slightly bringing down the caffeine and just wean yourself back to getting to the place where you just have one cup of coffee in the morning – it’s a real treat! And focus on getting more stable energy throughout the day.

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