Q: I’ve heard that drinking coffee first thing in the morning can interfere with my ability to feel awake and can lead to an afternoon energy crash. Is that true?
It’s an idea that has been popularized by online influencers: Avoid consuming caffeine for 90 to 120 minutes after waking up, they say, and you will perk up more naturally, thwart the dreaded afternoon slump and have better sleep.
Proponents explain the idea as if it’s supported by good evidence, with some people who have tried the method saying it has “been a game changer” for their energy levels.
But scientists who study the relationship between caffeine and sleep say that while there may be some benefits to putting off your morning coffee, there’s not much research to back them up.
In some cases, experts warn, the risks of delaying your morning caffeine could outweigh the purported benefits — or even be dangerous.
How Caffeine Works, and How Long It Lasts
Throughout the day, your body produces a chemical called adenosine, which binds to receptors in your brain and makes you feel drowsy. Caffeine perks you up by blocking those receptors, said Marilyn Cornelis, a caffeine researcher at the Northwestern University Feinberg School of Medicine.
But you don’t feel the stimulating effects of caffeine immediately after your first sip of coffee, said Michael Grandner, the director of the sleep and health research program at the University of Arizona. It takes about 20 to 30 minutes for caffeine to be absorbed into your bloodstream, reach your brain and make you feel more alert, he said.
How long caffeine keeps you sharp “varies considerably,” based in part on your genetics, Dr. Cornelis said.
Some people may have one morning brew and “ride that for much of the day,” she said. Others clear caffeine from their bodies more quickly and might want another cup within a few hours, she added.
“Everyone responds to caffeine differently,” Dr. Cornelis said, so there’s not a one-size-fits-all solution for timing your caffeine.
The Evidence For — and Against — Caffeine Delay
Because adenosine levels in your brain decrease while you sleep, they’re at their lowest immediately after you wake up, Dr. Grandner said. So with little adenosine present for caffeine to block, a cup of coffee first thing will give you less of a boost — or “less bang for your buck,” as Dr. Grandner said — than when adenosine levels are high.
This may be one rationale for delaying your caffeine in the morning, Dr. Grandner said. He often waits for 30 to 60 minutes after waking to have his first cup of coffee, but there are no studies on what the optimal timing should be; it’s more about personal preference, he said.
Another potential reason to delay your morning caffeine is if you want to have caffeine only once per day, Dr. Cornelis said. Timing it for later in the morning could help extend its effects into the early afternoon, potentially countering any drop in alertness at that time.
That said, there’s no harm in having caffeine first thing, Dr. Grandner said.
Although some online proponents suggest that doing so will disrupt your body’s normal waking process by interfering with the natural rise of cortisol, there is little evidence for this. The few small studies that have examined caffeine’s influence on cortisol have found that in those who consume caffeine regularly, it has little effect on morning cortisol levels, said Allison Brager, a neurobiologist for the U.S. Army.
The reality is that many people don’t get enough sleep, so if you need to be alert first thing in the morning, caffeine can be a lifesaver, Dr. Brager said. Research has shown that caffeine can enhance mental sharpness and physical performance. For soldiers driving heavy trucks, firefighters working overnight shifts or surgeons scrubbing in for early morning procedures, delaying caffeine “can be a recipe for disaster,” Dr. Brager said.
If you’re an early morning exerciser, she added, it makes sense to have caffeine as soon as possible because it may improve your workout.
It’s also fine to have another cup of coffee (or other source of caffeine) if and when your energy levels wane around midday, Dr. Grandner said. Just avoid having it within six hours — or eight to 12 hours, if you have trouble falling asleep — before bedtime, he added.
If you feel like you need caffeine throughout the day just to function, consider seeing a sleep specialist, Dr. Grandner said; you may have a treatable disorder like insomnia or sleep apnea.
And keep in mind, Dr. Grandner added, that coffee and tea provide more than just caffeine: The drinks are also great sources of antioxidants and beneficial plant-based compounds, which may explain some of their health advantages.
Coffee also helps many people have regular bowel movements. And for most of us, a morning coffee ritual offers a simple source of pleasure. What could be more optimal than that?
