Coffee, tea or sleep? Here’s when to wisely consume caffeine, what qualifies as too much and what to know about why it affects each of us differently.

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Many of us start our days the same way: with a cup of coffee or tea. Caffeine is as much a part of our routine as brushing our teeth or getting dressed for the day.
Maybe your habit extends to a cup of coffee in the afternoon, or you have a soda with your dinner.
And maybe as a result, you lie in bed awake later thinking of where you went wrong instead of getting needed sleep.
Rob M. van Dam, a researcher in epidemiology and nutrition from the National University of Singapore, explains when to wisely consume caffeine, what qualifies as too much and what to know about why it affects each of us differently.
This interview has been condensed and edited for clarity.
Different people can react very differently to caffeine.
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CNN: How do we know when it’s time to stop drinking coffee during the day so we can still get a good night’s sleep?
Rob van Dam: That sounds like a simple question, but unfortunately there’s not one answer to it. And that’s because different people react very differently to caffeine.
If you’re getting tremors, feeling suddenly nervous, or your heart rate is changing, it could well be that you’re drinking too much caffeine. And similarly, it can interfere with a good night’s sleep.
You may want to say, “Well, let’s try to cut down caffeine and not drink it after a certain time in the afternoon and see if that improves my sleeping habits.” So it’s really something every individual has to experiment with for themselves how much caffeine they drink and when they drink it.