Best time to drink coffee: Experts spill the beans

Rise and grind?

Some social media users, recently, have been blaming their afternoon slumps on drinking coffee first thing in the morning. But is there any truth behind it?

While researchers, who study the relationship between caffeine and sleep, say that there may be some benefits to delaying a cup of joe, there’s not much research to back it up. 

Michael Grandner, a professor and director of the Sleep and Health Research Program at the University of Arizona, said that adenosine – a neurotransmitter that builds up in the blood and brain while awake – is what can make a person feel drowsy and inhibit processes associated with wakefulness. 

"Caffeine works by blocking adenosine, but adenosine levels are lowest first thing in the morning," Grandner told FOX Television Stations. "Also, natural sleep inertia drops in the first hour of awakening. Perhaps it is optimal to caffeinate about an hour after waking up so that you get more benefit from it." 


A customer carries a cup of coffee to her table. (Credit: Bryan Thomas/Getty Images)

Marilyn Cornelis, a PhD and associate professor at the Department of Preventive Medicine at Northwestern University, echoed a similar sentiment, citing the cortisol awakening response. 

According to the National Library of Medicine, the cortisol awakening response (CAR) is a physiological process that occurs when the adrenal glands increase cortisol secretion after waking up. This increase in cortisol levels typically peaks 30–60 minutes after waking and can help prepare the body for the day's demands.

"If using (regular) coffee to wake up in the morning, it may be ideal to wait an hour upon waking to allow your body to first naturally wake up," Cornelis told FOX.

Dr. Deborah Lee, a U.K.-based doctor, also said in a statement to Fox News Digital that drinking coffee first thing in the morning might not be the best bet. 

"Elevated levels of cortisol may impact your immune system, and if they’re already at their peak when waking up, drinking coffee as soon as your eyes open may do more harm than good, and may even make you immune to caffeine over a long period of time," Lee explained

Taking this rhythm into consideration, Lee suggested that the best time to have caffeine would be at least 45 minutes after waking up, when "your cortisol rhythm starts to dip."

"The best time to drink coffee would typically be mid-to-late morning, when your cortisol is a lot lower and you start to feel that energy slump," she added. 

Delaying coffee consumption

Cornelis noted that delaying caffeine intake may also reduce the amount of caffeine a person ends up needing throughout the day. 

If coffee is a tool to maintain alertness or focus, she said a person can strategize when they take the caffeine, knowing they will feel the effects within about 30 minutes of intake.

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However, she noted that individuals metabolize and respond to caffeine differently, so the length of a coffee’s effect will depend on individual factors. 

For example, she said smokers metabolize caffeine much more quickly than non-smokers to clear caffeine from their system faster. She said genetics also play a role.

Don’t drink coffee in the evening

But don’t wait too long to drink it.

Most experts agree that drinking coffee near bedtime is never the best time.

"The main issue with caffeine is that most people will want to avoid it within about 6 hours of planned bedtime so it does not interfere with sleep," Grandner explained. "Some people can feel the effects even 10 or 12 hours after consuming it."

This means if a person’s bedtime is at 10 p.m., consuming caffeine should happen no later than 4 p.m.

Previous studies have also shown that drinking coffee late at night can impact a person’s sleep. 

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A team of researchers in Scotland looked at how late in the day a person could drink coffee without worrying about the caffeine keeping them up at night. 

They found that people should stop drinking caffeine six hours before bed. After that, it can mess with a person's internal clock.

The verdict

Bottom line: It is suggested that the best time to drink coffee is mid- to late-morning when a person's cortisol level is lower, but research on this topic is lacking.

And while mid-morning may likely be best, Dr. Wendy Troxel, a Utah-based sleep expert and senior behavioral scientist at the RAND Corporation, suggested that coffee drinkers experiment with what works best for them.

"For some people, waking up and having a glass of water to rehydrate and then having coffee works well — but for others, the morning ritual of having a cup of coffee first thing upon awakening is just too good to give up," she said. "So, I think it’s mostly a matter of personal preference."

Cornelis added: "I go to the gym first thing and use caffeine for a ‘boost’, so I don’t have time to wait around … there is no reason to delay caffeine intake except that it may be slightly less effective immediately upon awakening and may fade sooner." 

This story was reported from Los Angeles.