What is the best time of day to drink coffee?

‘Consuming coffee during peak cortisol production greatly diminishes the caffeine’s effect’

Bill Murray and Andie Macdowell in Groundhog Day (1993) (Rex Features)

It’s a familiar tale. You wake up with a jolt as the piercing sound of your alarm interrupts your morning slumber. You roll out of bed, eyes half open and there’s only one thing on your mind:  your morning cup of coffee.

For many people, having coffee as soon as they wake up is not just a part of their daily routine, it’s a necessity. They feel that they wouldn’t be able to function without a steaming cup of joe first thing in the morning.

And yet, according to scientists, not only can it be detrimental to drink coffee at the very start of the day, but there are certain times later on that are better-suited for caffeine consumption to maximise its effects.

Here’s everything you need to know.

Why does it matter what time of day you drink your coffee?

Cortisol, otherwise known as the “stress hormone”, is secreted by the body’s adrenal gland when you are feeling particularly stressed.

But it is also secreted throughout the day as a natural part of the body’s circadian rhythm, making you feel increasingly alert.

When your cortisol levels are at their highest, it is advisable not to consume coffee, as doing so may result in your body developing a tolerance to caffeine.

This could mean that in future, you would need even more coffee in order to feel awake.

“Cortisol production is strongly related to your level of alertness and cortisol peaks for your 24 hour rhythm between 8 and 9am on average,” neuroscientist Steven Miller, a senior medical science liaison at Greenwich Biosciences, wrote in a blog post in 2013.

“One of the key principles of pharmacology is use a drug when it is needed. Otherwise, we can develop tolerance to a drug administered at the same dose,” he explained.

“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.”

In a video created by AsapScience, a YouTube channel run by internet personalities and scientists Mitchell Moffit and Gregory Brown, they explain that the body’s circadian rhythm, the “internal biological clock”, determines “how sleepy we are during the day”.

When your cortisol levels peak between 8am and 9am, this indicates that “your body has a natural mechanism to wake you up”, the video states.

“And while you may think that caffeine can complement this mechanism, 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.”

In a study published in the British Journal of Nutrition earlier this year, James Betts, co-director of the Centre for Nutrition, Exercise and Metabolism at the University of Bath, explained that “blood sugar control is impaired when the first thing our bodies come into contact with is coffee”, particularly if did not sleep well the night before.

“We might improve this by eating first and drinking coffee later if we feel we still need it. Knowing this can have important health benefits for us all,” he said.

After assessing 29 male and female participants for their study, the researchers concluded that when a night of bad sleep is combined with coffee first thing in the morning, this can lead to the body’s blood glucose response to breakfast rising by approximately 50 per cent.

What are the best times of day for drinking coffee?

In addition to 8am to 9am, on average, people’s cortisol levels are said to peak between 12pm and 1pm and between 5.30pm to 6.30pm in the afternoon, Miller says.

If you are a coffee drinker, it would therefore be advisable to drink coffee in between these times in order to reap the benefits and avoid building a tolerance to caffeine.

But what about if you wake up particularly early or enjoy regular lie ins?

According to AsapScience, “scientists have actually found that cortisol levels do indeed increase about 50 per cent right after you wake up, regardless of the time”.

With this in mind, irrespective of the time you get up in the morning (or afternoon), if you want to make the most of your cup of coffee, it would be advised that you wait at least an hour before turning on the kettle.

Is it ok to drink coffee late in the afternoon?

Despite the advice to circumvent cortisol peak times when choosing when to drink coffee, consuming caffeine in the mid or late afternoon can have a significant impact on your ability to sleep.

Registered nutrition consultant Jenna Hope explains to The Independent that caffeine “has a half life of six hours”, which means that if you have coffee at 4pm, by 10pm, “half of the caffeine remains in the bloodstream”.

“Caffeine impairs the release of the neurotransmitter adenosine,” Hope says.

“Adenosine is released slowly throughout the day leaving you feeling sleepy by the evening. When adenosine is impaired you can be left feeling wired which can impair sleep.”

Samantha Briscoe, lead clinical physiologist at London Bridge Hospital, adds that it is not only the time of day that people need to make note of when drinking coffee, but how much they consume.

“It is therefore recommended to have your last caffeinated beverage no later than 2-3pm and consume no more than the recommended 400mg per day,” Briscoe states, which would equate to around four cups of coffee.

Dr Nerina Ramlakhan, sleep expert at Silentnight, recommends replacing your normal cup of afternoon coffee “with herbal tea or decaffeinated variants of tea and coffee, particularly if you find that you wake up feeling unrefreshed and sluggish despite having slept for eight or more hours”.