For many people, an afternoon coffee is the fuel that carries them through the rest of the day. But drinking caffeine too close to bedtime can make falling asleep—and staying asleep—far more difficult.
Around two-thirds of Americans drink an average of three cups of coffee daily. Sleep experts recommend setting a caffeine cutoff to prevent the habit from interfering with nighttime rest.
So, exactly how late is too late for daytime coffee?
A resurfaced study suggests that avoiding caffeine for only a few hours before bed may not give the body enough time to recover. If you believe stopping at 5 p.m. is sufficiently early, the research offers a reason to reconsider.
After reviewing findings from 24 studies, researchers in Australia concluded that people should have their final cup of coffee at least nine hours before going to bed to minimize sleep disruption.
That means anyone aiming to fall asleep at 10 p.m. may want to switch off the coffee machine shortly after lunch.
For gymgoers who rely on caffeinated pre-workout products, the window is even shorter. These supplements often contain considerably more caffeine than a regular cup of coffee.
Researchers estimated that pre-workout caffeine should be stopped at least 13 hours before bedtime.
A meta-analysis found that the final cup of coffee should be consumed at least nine hours before sleep
Caffeine works by blocking adenosine, a chemical that naturally accumulates during the day and helps create the growing drive to sleep as bedtime nears.
When adenosine’s effects are blocked, the body remains more alert. Heart rate may rise, while blood vessels in the brain constrict. Normally, those vessels widen during rest to support oxygen flow, but caffeine can limit that response and contribute to higher blood pressure.
A typical cup of coffee contains about 80 to 100 milligrams of caffeine. Tea generally has 15 to 70 milligrams, while energy drinks can contain between 80 and 300 milligrams. Pre-workout supplements vary, but commonly provide roughly 150 to 300 milligrams per serving.
The FDA advises adults to consume no more than 400 milligrams of caffeine a day—roughly the amount in four cups of coffee. Excessive intake can affect cardiovascular health, potentially causing heart palpitations, an elevated heart rate and high blood pressure.
Published in 2023 in Sleep Medicine Reviews, the study examined 24 investigations into the connection between caffeine consumption and poor sleep.
The researchers assessed how both the amount and timing of caffeine affected sleep, including total sleep loss, the time needed to fall asleep and overall sleep quality.
Based on the combined findings, they calculated that a cup of coffee containing approximately 107 milligrams of caffeine should be consumed at least 8.8 hours before bedtime.
For someone who goes to bed at 9 p.m., that would place the final coffee at about noon. With a 10 p.m. bedtime, the recommended cutoff would be around 1 p.m.
MORE STORY: Gypsy Rose Blanchard After Prison: Life Following Boyfriend’s Death
Larger caffeine doses require an even earlier stop, the researchers found. A typical caffeinated pre-workout serving—roughly equivalent to two standard 8-ounce cups of coffee—should be taken no later than 13.2 hours before bed.
As a result, someone going to sleep at 11 p.m. would ideally avoid taking a caffeinated pre-workout supplement after about 9:30 a.m.
The research identified several associations between caffeine and disrupted sleep. Most notably, consuming caffeine after the recommended cutoff was linked to an average reduction of 45 minutes in total sleep time.
Another finding looked at sleep efficiency – the amount of time spent actually asleep.
Late night caffeine also reduced sleep efficiency by about seven percent, roughly 34 additional minutes spent awake. This means someone who spent eight hours in bed could have spent more time struggling to fall asleep or waking during the night.
Caffeine also increased the time it takes to fall asleep by about nine minutes and was associated with waking up more in the middle of the night.
If someone woke up after initially falling asleep, caffeine before bed could add about 12 minutes to their total time awake during the night.
Caffeine was also linked to less deep sleep, which is crucial for overall immune support, cardiovascular health and energy restoration.
The findings showed that the subjects spent an extra six minutes in a light sleep stage and lost 11.7 minutes of deep sleep.
Coffee has been found to knock out peoples deep sleep, with those who drink it too close to bed experiencing fewer delta brain waves, linked to deep sleep and more beta waves associated with wakefulness
Around 80 percent of US adults consume some form of caffeine every day.
In addition to when to stop drinking caffeine, experts generally recommend holding off on the first cup of coffee until 90 minutes after waking up in order to reap the top energizing benefits and avoid jitters immediately after waking up.
Studies show cortisol levels, the main stress hormone, are highest when we wake up and that having a coffee too early boosts these even more.
High cortisol keeps your body in a ‘fight-or-flight’ mode, which can disrupt sleep, metabolism and energy. It can also cause feelings of anxiety, exhaustion, insomnia and brain fog.
Looking to cut back on caffeine and sleep better? Experts recommend tea as a sound alternative, as it contains less caffeine and has added antioxidants, offering a more moderate caffeine boost without packing the same punch as coffee.
Green tea offers less caffeine than coffee and contains L-theanine, an amino acid found in tea leaves and mushrooms. It promotes calm and focused relaxation.
An 8oz cup of green tea has about 29mg of caffeine, which can help wake you up without drastically affecting sleep.