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The Best Time Of Day To Drink Coffee

Think 8 a.m. is the perfect time for a big dose of caffeine? Think again.

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Ever wonder what the best time is to drink your coffee? You probably know it is not a good idea to drink part of your daily dose of caffeine in the afternoon. Especially for those who have problems sleeping. But, do you ever drink your coffee and feel like it just didn’t work? I know I have that feeling sometimes. The explanation for this has to with a concept that I think is extremely interesting but rarely discussed: chronopharmacology.

Chronopharmacology can be defined as the study of the interaction of biological rhythms and drug action. One of the most important biological rhythms is your circadian clock. This endogenous 24-hour clock alters your physiology and behavior in variety of ways but it can also alter many properties of drugs including drug safety (pharmacovigilance), pharmacokinetics, drug efficacy, and perhaps even drug tolerance.

Image: Flickr user tmblue

But, what part of the brain produces this 24-hour cycle and what signals does it receive in order for it to do so properly? It has been known for a long time that light is a strong zeitgeber. A zeitgeber is a term used in chronobiology for describing an environmental stimulus that influences biological rhythms. In the case of mammals, light is by far the most powerful. Following the discovery of connections between the retina and hypothalamus (the retinohypothalamic tract), investigations were aimed at the hypothalamus as the putative master clock. Indeed, in some of the most elegant brain lesion experiments, Inouye and Kawamura (1979) provided some of the first evidence demonstrating that the hypothalamus acts as the master clock in controlling the circadian rhythm. By creating an "island" in the brain by methodically cutting the hypothalamus away from any surrounding tissue, the circadian clock was completely lost (Inouye and Kawamura, 1979).

What does that mean? Well, the output of the hypothalamus nucleus (the suprachiasmatic nucleus or SCN) that controls the circadian clock has a variety of functions. The SCN controls your sleep-wake cycle, feeding and energy consumption, sugar homeostasis, and in addition to a few other things it controls your hormones. And, with respect to your alertness, the SCN’s control of cortisol (often referred to as the "stress" hormone) production is extremely important.

Most readers here enjoy–-and desperately need-–their morning coffee. But if you are drinking your morning coffee at 8 a.m., is that really the best time? The circadian rhythm of cortisol production would suggest not.

Image: Flickr user Daniel Sofer

Drug tolerance is an important subject, especially in the case of caffeine since most of us overuse this drug. Therefore, if we are drinking caffeine at a time when your cortisol concentration in the blood is at its peak, you probably should not be drinking it. This is because cortisol production is strongly related to your level of alertness and it just so happens that cortisol peaks for your 24-hour rhythm between 8 a.m. and 9 a.m. on average (Debono et al., 2009). Therefore, you are drinking caffeine at a time when you are already approaching your maximal level of alertness naturally.

One of the key principles of pharmacology is use of a drug when it is needed (although I’m sure some scientists might argue that caffeine is always needed). Otherwise, we can develop tolerance to a drug administered at the same dose. In other words, the same cup of morning coffee will become less effective and this is probably why I need a shot of espresso in mine now.

Although your cortisol levels peak between 8 a.m. and 9 a.m., there are a few other times where—on average—blood levels peak again, like between noon and 1 p.m., and between 5:30 p.m. and 6:30 p.m. In the morning then, your coffee will probably be the most effective if you enjoy it between 9:30 a.m. and 11:30 a.m., when your cortisol levels are dropping before the next spike.

A version of this article originally appeared on provides information about the field’s understanding of causes, symptoms, and outcomes of brain disorders. The site is a public information initiative of The Kavli Foundation, the Gatsby Charitable Foundation, and the Society for Neuroscience, all leading global nonprofit organizations working to advance brain research. Leading neuroscientists from around the world form the editorial board.

[Gif adapted from Trevor Southworth]

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  • Jack Sullivan

    Actually, research from the 70s shows that the brain works on a 25 hour cycle. The world turns on a 24 hour cycle.

  • Carson

    This guy needs to take a journalism course. It took him the length of the entire article before he actually got to the meat and potatoes of the article, i.e. what are the best times of the day for drinking coffee. Anyway, once I found the information I was looking for I found it useful.

  • John Lapolla

    Simple formula. Java juice takes 20-30 minutes to hit my bloodstream. Therefore the best time to enjoy that hot, fragrant cup of Joe is 20-30 minutes before I fall asleep at my desk. Repeat as needed. Problem solved.

  • Kathryn Ananda

    i wondered about that... not that i do! but curious about the influence of personal circadian rhythms, that can vary significantly, and what factors are actually involved...

  • Fred Firestine

    A couple of months ago, I heard about the benefits of a caffeine "fast" for a week, to reset the body's tolerance (and need for increasingly more coffee to feel the buzz). I just did this for the second month in a row (last week of the month), and it seems to work nicely. I blogged about my first month's experience, which includes a warning to ease into it over a few days rather than "cold turkey." Even so, I did experience some unpleasant side effects. I think it's worth it for the rest of the month, though.

  • Rubie

    What a lovely example of how stupid scientists can be. It's Monday morning, at 8.20; so, I shouldn't drink coffee right now even though I feel like a zombie - I should wait an hour and 10 minutes because, according to this article, I'm actually at my most alert right now. (I just had the coffee, in case you were wondering)

    I also had no idea that the circadian clock was wound up exactly the same way for every coffee drinker in the world, regardless of when they go to bed or wake up

  • L L Bennett

    Are we not a little cranky at 8:20 Monday mornings? Better have another cup!

  • ILikeFish

    Just because the article was dumb doesn't mean the study was. I hate the over simplification of science by the media.

  • Arthur Perez

    I reckon there is a 'habit' effect too that is added at the top of the scientific read. Therefore, we add more human in the science.

  • Anna

    What about before 8 am?
    Also, how do I stop the sound from coming from the banner at the top of this article. There's no way to stop it. It's so annoying I had to turn my sound off.

  • Steven Miller

    , if light is coming on earlier in the day, you will experience your greatest peak cortisol levels are earlier times. And visa versa.

  • Steven Miller

    you are correct in this. Although you might get some caffeine into your blood, it might take about 20-30 minutes before you feel an effect. So, if you start having coffee/soda or whatever right after your blood cortisol peaked (and is starting to drop) you will then be compensating appropriately to stay altert until it starts to rise (and it does not rise as dramatically near lunch time as it did in the morning).

  • dflanigan

    yeah... except we are not talking about intravenous caffeine injections here: you need to consider the time it takes after coffee consumption for the caffeine to be absorbed and metabolized. Peak blood concentration is after about an hour and if I remember my pharmacology and toxicology classes well, the half life of caffeine in adults is about 6 hours (which of course can vary widely depending on health and genetics of individuals).