Many of us rely on an afternoon coffee to power through the day, but drinking it too late can leave you tossing and turning at night.
About two-thirds of Americans drink, on average, three cups of coffee per day. Experts advise coffee lovers to have a cutoff time so it doesn’t impact their nighttime sleep.
But how late is too late to drink coffee during the daytime?
A resurfaced study shows that giving up caffeine just a few hours before bed may not nearly be enough time to wind down. So if you think nixing the caffeine around 5pm is early enough – think again.
After analyzing data from two dozen studies, researchers in Australia found that your last cup of coffee should be at least nine hours before bed to avoid disrupting a good night’s rest.
This means if you’re trying to doze off by 10pm, it’s best to turn off the coffee machine just after lunch.
And for gymgoers who use a caffeinated pre-workout supplement for an energy boost – the cutoff time is even longer due to higher caffeine content.
The experts found a cutoff time of at least 13 hours before bed.
A meta-analysis study concluded your last cup coffee should be consumed at least nine hours before sleep
Caffeine blocks adenosine, a natural chemical that builds up throughout the day and drives the urge to sleep as bedtime approaches.
Once adenosine accumulation stops, the body feels more awake and alert, heart rate can increase and the brain’s blood vessels constrict. The blood vessels usually widen to allow more oxygen during rest, but caffeine can prevent this and lead blood pressure to go up.
The average cup of coffee contains between 80 to 100mg of caffeine, while tea has 15 to 70mg and energy drinks have anywhere from 80 to 300mg. The amount of caffeine in pre-workout supplements varies but tend to be around 150 to 300mg.
The FDA recommends Americans get no more than 400g of caffeine per day, which is about four cups of coffee. Higher amounts of caffeine can cause cardiovascular health harms, such as heart palpitations, high heart rate and high blood pressure.
In the 2023 study, published in Sleep Medicine Reviews, researchers sifted through 24 studies that analyzed the relationship between caffeine intake and poor sleep.
Researchers then examined how caffeine dose and timing affected sleep, including how much sleep was lost, how long it took to drift off and overall sleep quality.
Using these findings, researchers estimated that one cup of coffee containing about 107mg of caffeine should be consumed at least 8.8 hours before bedtime.
If you normally go to bed at 9pm, you should have your last coffee at around 12pm. If bedtime is at 10pm, the last coffee should be at 1pm, and so on.
And higher caffeine doses need an earlier cutoff, researchers found. An estimated serving of caffeinated pre-workout drink, equivalent to about two standard 8oz cups of coffee, should be stopped 13.2 hours before bed.
So if you go to bed at 11pm, you should not be taking pre-workout after 9.30am.
The research team found several links between caffeine and poor sleep. First, caffeine consumption after the recommended cutoff times was associated with an average 45-minute reduction 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.
