Maybe your habit has increased to a cup of coffee in the afternoon, or soda with your meal.
And maybe as a result, you later wake up and sit in bed wondering where you went wrong rather than needing sleep.
Researcher in epidemiology and nutrition of National University of Singapore, Rob M. Van Dam explains when to consume caffeine, what is highly qualified, and why it affects each of us differently.
This interview is condensed and edited for clarity.
CNN: How do we know if it’s time to stop drinking coffee during the day so that we can still have a sound sleep?
Rob van Dam: This seems like a simple question, but unfortunately there is no answer. And that’s because different people react to caffeine very differently.
If you are feeling shivering, suddenly feeling nervous, or your heart rate is changing, it may well be that you are drinking too much caffeine. And likewise, it can interfere with a good night’s sleep.
You may want to say, “Well, let’s try to cut down on caffeine and don’t drink it after a certain time in the afternoon and see if it improves my sleeping habits.” So this is really something that everyone has to experiment with for themselves – how much caffeine they drink and when they drink it.
CNN: How are we affected by caffeine?
Van Dam: Your lifestyle makes a difference. For example, people who smoke fast caffeine twice in the liver. If you are a smoker, it is possible that you can drink caffeine till later and still recover in case of sleep.
But there are other factors, such as if you as a woman use oral contraceptives, it takes twice as long to metabolize caffeine. It could be that you were able to drink caffeine in the evening and still sleep well, and then you start using oral contraceptives and you can see that you can’t sleep anymore.
Genetics also plays a role, as some people have changes in the genetic code that affect enzymes in the liver that relieve metabolism and caffeine. You can also slow or accelerate it.
CNN: How high is caffeine?
Van Dam: In general, it is recommended by organizations such as the US Food and Drug Administration to keep caffeine at 400 mg per day or less. If you look at the typical 8-ounce cup of coffee, which contains about 100 milligrams of caffeine, it will be up to four cups of coffee per day.
Another recommendation is to keep it no more than 200 milligrams per meeting. Even though you can drink four cups a day, you don’t want to drink four cups at once – which would be too much for the body to metabolize, at least for most people.
CNN: Is Caffeine for Everyone?
Van Dam: Caffeine actually lifts you up a bit and makes you more alert. Therefore it can be beneficial, especially for people with routine tasks. For example, if you must drive a lot at night, or if you are in the military and you are on duty to monitor, but nothing is actually happening for a few hours.
But not everyone will need it. You can have enough energy or get a good sleep which you can go through in the day without any caffeine.
And if you don’t want to, there is no reason to drink it. Because even if you like the taste of coffee, you can always drink decaffeinated coffee, and there is nothing wrong with that.
CNN: Is Caffeine Safe?
Van Dam: Recently, people have been very concerned about caffeine in relation to cancer risk, cardiovascular risk, or other health consequences. And research on that has indeed been very reassuring. By far, coffee is probably one of the most studied drinks.
So, if you are enjoying coffee, then you are enjoying caffeine, and you can consume it in small amounts and you have no harmful effects – you really have a lot more to say about the health effects of coffee. No need to worry or caffeine.