Category: Nutrition


How Late is Too Late for Coffee?

I, like many of you, have often wondered about the notion of drinking a cup of coffee after the evening meal. People often say things like, “I can’t drink coffee after 4PM or I won’t be able to sleep,” and this seems to make sense. Others, like myself, can enjoy a coffee after dinner seemingly without any consequences, as far as sleep is concerned.

To help shed some light on this issue, researchers publishing in the Journal of Clinical Sleep Medicine recently reported the results of study in which individuals consumed 400mg of caffeine 0, 3, or 6 hours prior to their normal bedtime. These folks were compared to a similar group of people who received a placebo. Sleep was measured by self-reporting as well as through the use of a portable sleep monitor.

The results showed that even when caffeine was consumed 6 hours before bedtime, there was a remarkable disruption of sleep. This was found to be associated with an average loss of sleep of 41 minutes as well as doubling the time it took these subjects to fall asleep. 

On the other hand, compared to placebo, caffeine consumption 6 hours prior to bedtime did not seem to affect the amount of wakefulness during the sleep period or the actual quality of sleep. Consuming caffeine 3 hours before bedtime, however, was clearly associated with disruption in the quality of sleep. 

Overall, the researchers of this small study of 12 individuals concluded that caffeine consumption at this dosage, and at these times prior to sleep, is significantly disruptive of this important and restorative bodily function.

My take on this report is that for those of us who might drink a coffee late in the day and don’t think much of it, the research would argue that there may indeed be consequences that are not readily apparent that could be harmful in the long run.

 So maybe decaf will turn out to be the best choice after dinner.

  • Courtney Schmidt

    I can’t have decaf either late in the day or it disrupts my sleep too!! I’ve tried several times! But I could drink a caffeinated soda with dinner with less effects, it seems. Which is weird. I don’t get it. But that’s me!

    • David Perlmutter

      If you know it doesn’t work for you Courtney, then best to avoid! Have to work on the plan that’s right for you and your body.

  • Lynn Dell

    Good to know. I like drinking a product from KeVita, which is their lemon-cayenne probiotic drink. It tastes like fizzy lemonade, and one of the cultures is l.rhamnosis. Good for unwinding, and extremely low in sugar, unlike their other probiotic brews.

  • DeAnn Morgan

    I have other issues with drinking coffee that disrupts my quality of sleep, I used to believe it was caused by caffeine but now believe it is something else. 1 cup of coffee in the morning will cause me to clench my teeth at night while I sleep and if I continue daily drinking coffee (3 days in a row) I develop white spots on my finger nails that my acupuncturist says is calcium deficiency. When I stop drinking coffee and drink CALM in the evening the clenching stops and the white spots fade away on my nails. CALM is a Magnesium supplement developed by Peter Gillham.
    If I drink black tea anytime during the day I don’t experience clenching or white spots on my nails which tells me it is not caffeine that is causing the problem. So now I am researching what is in coffee besides caffeine, something that may be pulling the calcium/magnesium away from the bones or not letting it get absorbed from the diet??? If anyone has any insight please share.

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