It makes a difference what time you drink coffee during the day

August 11, 2016 4 min read

It makes a difference what time you drink coffee during the day

Timing when you drink coffee may improve your health and quality of life. 19th century French School painting by an unknown artist (Wikimedia Commons image)

Did you know timing when you drink coffee intake may improve your life? In the morning when the alarm goes off, the first thing many people think of is getting a coffee fix. Coffee or tea doesn’t just taste good, the ritual is not just comforting, you actually needthe caffeine to feel alert, normal and ready to face the day. And if you’ve developed a dependence on caffeine, you might even get a headache, be crabby and out of sorts or be too sleepy to perform well if you dont’t get it.

But what if we told you this is all wrong? That it’s better to wait until mid-morning to drink your coffee, tea or energy drink, or you could risk fatigue or even poor quality of life?

Feeling sleepy or awake

It has to do with body chemistry and the circadian rhythm or the body’s internal clock, which regulates when you feel awake or sleepy. When you first get up, your body produces the stimulating “stress hormone” cortisol, which helps you wake up and be alert after a night’s sleep.  But if you take caffeine first thing, this may induce the body to produce less cortisol, which could make you tired and dependent on caffeine.

A 2009 study published in The Journal of Clinical Endocrinology and Metabolism says there are three times during the day when the body’s cortisol levels are at their highest: between 6 and 10 a.m., from noon to 1 p.m., and from 5:30 to 6:30 p.m. The very highest levels of cortisol peak between 8 and 9 a.m.

Timing when you drink coffee

So take your caffeine around 9:30 to 11:30 a.m. and again between 1:30 and 5 p.m.

The peak cortisol time frame varies some from person to person depending on when they wake up, but these are considered normal waking hours. A person’s weight and gender do not seem to make these peak times vary, the study said.


A scientific study narrowed down quite precisely the times of highest cortisol levels in the human body. Note the peak at around 8 to 9 a.m.

The scientific study states: “Cortisol has a distinct circadian rhythm regulated by the brain’s central pacemaker. Loss of this rhythm is associated with metabolic abnormalities, fatigue, and poor quality of life.”

Video explains cortisol/caffeine connection

A short video from the popular science YouTube channel AsapSCIENCE explains the phenomenon of cortisol, caffeine and the morning routine:

“What if I told you you’ve been drinking your coffee incorrectly this entire time?” the narrator of the video asks. “Scientists have actually found that consuming coffee or energy drinks during peak cortisol production greatly diminishes the caffeine’s effect and builds up a greater tolerance to the drug in the long run. Overall that means you get less of a buzz and need even more to stay awake in the future. Science says wait at least an hour to take your cup of joe, and your body will be optimally ready to go.”

The video says the best time to drink coffee is during non-peak times. This is when your body needs the boost, and also it is less likely that the caffeine will interfere with your body chemistry and circadian rhythms if you take it then. Of course, many people have trouble getting to sleep if they take caffeine later in the day, so you might want to avoid a cup of java or tea in the 5:30 to 6:30 p.m. peak cortisol time frame.

Caffeine and melatonin

Also, NPR reports on a study that gave participants a double shot of espresso three hours before bedtime that showed the dose of caffeine slowed release of another body chemical, melatonin, by about 40 minutes. Melatonin is a human hormone that helps people get to and stay asleep.

“We found that caffeine did indeed, in the evening, shift your clock later,” sleep and circadian physiologist Kenneth Wright told NPR. “It was about half the effect the scientists noticed when they instead exposed the volunteers to bright light. What we’re seeing here now is another way that caffeine impacts our physiology that we didn’t know about before in humans.”

A tolerance for caffeine

The Washington Post reports that when people talk about developing tolerance for caffeine, they are unknowingly referring to inhibition of cortisol production.

“Coffee drinkers who are exhausted in the morning without their coffee have likely altered their circadian rhythm in such a way that they need the caffeine boost in order to reach the level of wakefulness they used to achieve without it,” the article states.

Caffeine taken habitually seems to replace cortisol. But you can have your coffee and drink it too by timing your caffeine intake during troughs in cortisol production.

Mark Miller
Mark Miller



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