How to Drink Coffee Better

Optimizing use of the world's most common drug

Author’s note: this piece was originally published in May 2019. It was updated for clarity and to reflect new research findings in February 2024.

The morning cup of coffee has an exhilaration about it which the cheering influence of the afternoon or evening cup of tea cannot be expected to reproduce.

Oliver Wendell Holmes, Senior

By some estimates, caffeine is the most widely-used drug in the world. About 1.6 billion cups of coffee alone are served on a daily basis. In the U.S., roughly 85 per cent of the adult population consumes at least one caffeinated beverage every day.

The fact, then, that more than 10,000 scientific articles on caffeine have been published should come as no surprise.

In the literature, there is mixed evidence regarding the health effects of consuming caffeine. The chemical may confer protective effects against cancer, neurodegenerative disorders, type two diabetes, and overall mortality (when limited to 200 to 300 mg daily) but might also contribute to bone loss and heightened levels of anxiety. Patients who are pregnant, have arrhythmias, or have GERD are also recommended to limit their caffeine intake.

Nonetheless, for those of us who indulge in coffee, science has much to say regarding the timing and form of caffeine consumption, carrying some surprising advice.

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When to Drink Coffee

The First Cup

Perhaps the two worst times to consume caffeine are immediately before getting into bed at night and directly after getting out of bed in the morning.

Shortly after waking, most healthy individuals experience a 50 per cent boost in levels of cortisol, a stress hormone that contributes to physical and cognitive alertness in preparation for daytime activity, in what is called the cortisol awakening response (CAR).

Figure courtesy of Taylor et al. (2016)

Cortisol peaks at about 30 to 45 minutes after waking and gradually decreases throughout the day.

Caffeine, meanwhile, reaches its peak plasma concentration about 30 to 60 minutes after consumption. For some individuals, however, this level might not be reached until 120 minutes post-consumption.

While high levels of caffeine will not necessarily interfere with CAR, a key tenet of clinical pharmacology is to only use a biologically active agent when necessary. If cortisol already provides the alertness desired upon rising in the morning, why bother drinking a cup of coffee and risking over-stimulation?

For a more advantageous use of caffeine, we should instead aim to consume our first cup of coffee about 30 minutes after waking.

Caffeine will then reach its peak plasma concentration after the cortisol awakening response has occurred. This timing is thereby likely to contribute to more sustained levels of alertness throughout the morning.

Andrew Huberman’s take

Andrew Huberman, a popular health podcaster, suggests the first cup of coffee should be consumed a full 90 to 120 minutes after waking. This period, he claims, allows cortisol to promote clearance of residual adenosine. Caffeine, which blocks the adenosine receptor to promote wakefulness, will thereby have fewer competing molecules and have a more robust effect. Huberman also states this timing may offset the late afternoon crash (as described below).

There is sparse evidence that cortisol reduces levels of adenosine (I could only find one very specific animal model suggesting a correlation) nor is there a body of literature showing that caffeine is more effective when plasma concentrations of adenosine are reduced.

I encourage piloting a short delay (30 to 45 minutes) compared to a long delay (90 to 120 minutes) in initiating caffeine consumption to determine if any perceivable changes are present between the two approaches.

An aside on bulletproof coffee

By the mid-2010s, many in the bio-hacker community were obsessed with “bulletproof coffee.” Adding a source of saturated fat, usually butter or medium-chain triglyceride (MCT) oil, to a cup of coffee would purportedly promote satiety and provide steadier energy throughout the morning.

A 2023 review of the available literature was damning:

There were no significant improvements in cognition, alertness, or energy levels from Bulletproof Coffee compared to regular coffee. The impact on hunger, satiety, resting energy expenditure, and fat oxidation appeared equivocal, with effects offset by the additional calorie intake of Bulletproof Coffee.

Until more robust evidence exists to support these claims, there is little reason to add saturated fat to your coffee, particularly given the well-documented relationship between saturated fat and cardiovascular events.

The Second Cup

For those who regularly consume caffeine, the first cup of coffee or tea is rarely sufficient to bring about the level of alertness to which they are accustomed. (Indeed, a tolerance to caffeine may develop after just three to five days of use in humans.)

Figure courtesy of Edwards et al. (2001)

Provided there are no high-valence stressors present, cortisol levels gradually decline throughout the day following their peak in CAR.

This drop in cortisol is not a major source of the dreaded early afternoon drowsiness that occurs between the hours of 2pm and 4pm for most adults based on vehicle collision data.

The National Sleep Foundation cites four important contributors to this “2:30 feeling:”

• Rapid decline in blood glucose levels following a spike from a meal replete with simple carbohydrates

  • This idea is not borne out by research. The afternoon dip is present even with a light lunch or no lunch at all. Other work suggests that high fat content in foods might lead to afternoon sleepiness.

• Neglecting to move for a prolonged period of time

• Mild dehydration

• Drop in body temperature, as per one's natural circadian rhythm

Exposure to natural bright light might help to attenuate this afternoon dip, as does a nap, face-washing, and caffeine consumption.

The effect of caffeine to boost wakefulness and attention may potentially moderate the effects of the afternoon lull as well as increase core body temperature, which is correlated with improved working memory and subjective alertness.

Should none of these other practices be effective, consuming another cup of coffee around 12 to 1 pm might help to abate the afternoon slump in cognition.

Given the latency of about 30 to 45 minutes for caffeine to reach its peak plasma concentration, this timing allows for its stimulatory effects to directly abut that feared bout of afternoon drowsiness.

Depending on one’s intended bedtime, however, the timing for this second cup may need to pushed to the late morning to avoid adverse effects on sleep.

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Harmful to the Last Drop: Caffeine and Sleep

Among individuals who consume caffeine, as many as 90 per cent have caffeine in the afternoon and almost 70 per cent consume caffeine in the evening (from 6pm to midnight).

The half-life of caffeine— the length of time needed to remove one-half of a given amount of an active substance— is roughly six hours. The quarter-life of caffeine is therefore about twelve hours. If you consume a cup of coffee at noon, which contains about 100mg of caffeine, you can expect 25mg to be present at midnight.

The threshold for improved auditory and visual vigilance may be as low as 32mg of caffeine, suggesting that some residual effects of even a single cup of coffee may be experienced nearly twelve hours post-consumption.

Indeed, a high amount of caffeine (400mg) consumed six hours before sleep initiation can prolong latency to fall asleep, reduce overall sleep duration, and diminish sleep efficiency. Even 200mg of caffeine (about two cups of coffee) consumed sixteen hours before the onset of sleep led to a significant decrease in total sleep time and efficiency as measured by EEG.

A recent systematic review concluded that a cup of coffee (about 100mg of caffeine) should be avoided about 9 hours before bedtime to avoid decrements in total sleep time.

Even one day of abstinence from caffeine, meanwhile, is associated with a longer duration of time spent asleep and higher quality of sleep.

Should these findings bring you pause, consider drinking green tea or black tea, which contain 35 and 60mg of caffeine, respectively, in lieu of coffee in the afternoon.

This reduction in caffeine consumption should allow for fewer sleep disruptions.

Alternatively, this additional dose of caffeine can be skipped altogether, a prudent choice to make if placing a premium on sleep.

Although caffeine can restore vigilance and alertness in sleep-deprived individuals, by no means is caffeine a substitute for obtaining a sufficient amount of rest, which for healthy adults of all ages is more than seven hours per night.

When sleep is restricted to as few as six hours, the cortisol awakening response is markedly blunted, contributing to excessive sleepiness upon rising. Immediate exposure to bright light, however, might help to elevate cortisol levels and compensate for this diminished response.

Whether one chooses to consume additional caffeine or utilize sources of bright light upon waking, there are absolutely no shortcuts to obtaining enough sleep.

In a forthcoming piece, I plan to detail the ravages of sleep deprivation, which include an increased risk of hypertension, type two diabetes, heart attacks, high cholesterol levels, depression, cancer, Alzheimer's disease, and suppressed immune function, all but negating whatever protective health effects coffee might offer.

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Caffeine and Antioxidants

Finally, I would be remiss to ignore that purveyors of coffee frequently taut its antioxidant content as an added bonus. Antioxidants decrease levels of oxidative stress, which damages the structure of DNA and contributes to the progression of cancer and aging.

• Coffee is the leading source of antioxidant intake among Americans.

• The antioxidant content is likely related to roasting of the beans.

  • Medium roasts tend to have the highest levels in some studies.

  • Other work suggests that coffee grown organically also contains higher levels.

• The ideal brewing method (as well as time and temperature) for maximizing antioxidant content has not been well established in the literature.

Family having coffee after a day’s work, 1937. Courtesy of the Library of Congress.