For many people, an afternoon coffee is a welcome boost. But drinking caffeine too close to bedtime can leave you wide awake when you should be sleeping.
Around two-thirds of Americans drink coffee, consuming an average of three cups a day. Sleep experts recommend setting a caffeine cutoff to prevent the habit from interfering with nighttime rest.
So, exactly how late is too late to drink coffee?
A resurfaced study suggests that stopping caffeine just a few hours before bed may not give the body enough time to recover. If you believe cutting off coffee at 5pm is early enough, the research offers a reason to reconsider.
After reviewing data from 24 studies, researchers in Australia concluded that people should have their final cup of coffee at least nine hours before bedtime to avoid disrupting sleep.
For someone aiming to fall asleep at 10pm, that means switching off the coffee machine shortly after lunchtime.
The recommended cutoff is even earlier for gymgoers who rely on caffeinated pre-workout supplements, which often contain substantially more caffeine than a standard cup of coffee.
Researchers found that these products should be stopped at least 13 hours before bedtime.
A meta-analysis concluded that the last cup of coffee should be consumed at least nine hours before sleep
Caffeine works by blocking adenosine, a natural chemical that 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 interfere with that process and contribute to higher blood pressure.
A typical cup of coffee contains about 80 to 100mg of caffeine. Tea generally contains 15 to 70mg, while energy drinks can range from 80 to 300mg. Caffeine levels in pre-workout supplements vary, but they commonly fall between 150 and 300mg.
The FDA recommends that adults consume no more than 400mg of caffeine per day—roughly the amount found in four cups of coffee. Excessive intake can affect cardiovascular health, potentially causing heart palpitations, a rapid heartbeat and elevated blood pressure.
In the 2023 study, published in Sleep Medicine Reviews, researchers examined 24 studies exploring the connection between caffeine consumption and poor sleep.
The team 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 findings, researchers estimated that a cup of coffee containing approximately 107mg of caffeine should be consumed at least 8.8 hours before bedtime.
If you usually go to bed at 9pm, your last coffee should be around noon. For a 10pm bedtime, the recommended cutoff is about 1pm, with the same calculation applying to other sleep schedules.
Larger caffeine doses require an earlier cutoff, according to the researchers. An estimated serving of caffeinated pre-workout—roughly equal to two standard 8oz cups of coffee—should be taken no later than 13.2 hours before bed.
That means someone who goes to bed at 11pm should avoid taking pre-workout after about 9:30am.
The research identified several associations between caffeine use 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.
