Millions of people across the world rely on an early morning shot of espresso to help them function through a groggy Monday morning and plenty more probably don’t even get to 12 o’clock before they require an emergency caffeine boost to avoid snoozing at their desk.
Due to caffeine’s oh-so-stimulating effects, the world has been trained to view coffee as a get-up and go early day brew and it’s therefore understandable that a lot of us avoid it before bed.
Because why would you want those same alerting effects when your body is more likely craving some rest and shut-eye?
But for those who just can’t get enough of the roasted bean, it’s a difficult quandary to decide when coffee o’clock officially ends.
Some people simply prefer a more creamy and indulgent coffee in the evening and others just love coffee so much that they can’t help but savour a naughty cup of joe right before bedtime.
Perhaps somewhat annoyingly, many late-night coffee drinkers also don’t seem to suffer half as badly from insomnia as those of us who accidentally downed one too many at 3 in the afternoon.
Which makes us wonder… is it really that bad to drink coffee before bed?
And if so… when should we be swapping our mochas for a hot glass of milk?
What New Studies Say About Coffee & Sleep
Going against everything we know and hold dear to us, recent scientific studies sent shockwaves through the coffee culture last year when they revealed a coffee before bed is not actually all that bad…
In an insanely long 14 years study, researchers from Harvard Medical School and Florida Atlantic University monitored 785 subjects’ quality of sleep along with their consumption of the UK’s three nastiest legal drugs: yes, it’s your old favourites, cigarettes, alcohol and caffeine!
Recorded over 5,164 days, researchers compared the consumption rates of these drugs with subjects’ sleep diaries. They also gave participants wrist sensors to get more conclusive data about their sleep duration and efficiency.
While those who smoked and drank booze nearly always suffered from varying levels of sleep disruption, the study quite confusingly found that coffee gluttons suffered next to no sleep interruption.
So what does it all mean?
Well, according to sleep expert Dr Neil Stanley, the results of this research merely indicate that the long-held belief that caffeine affects your quality of sleep is quite simply… a myth!
“For some people, the effects caused by caffeine are much lower and may not have any effects at all.” Dr Stanley told The Independent during an interview on common sleep myths.
“If you have been drinking two strong black cups of coffee every evening for the past 40 years and you have just developed a sleeping problem, then it is almost certainly not the coffee.”
Rejoice, late-night coffee slurpers!
However, for us day drinkers, this seems completely at odds with what we know, especially if you’ve ever personally sentenced yourself to a long night of tossing and turning after a cappuccino too late in the day.
It makes even less sense when you consider the many studies in years prior which have helped confirm our suspicions about heavy caffeine consumption throughout the day.
It’s a basic fact that caffeine suppresses melatonin, your sleep-regulating hormone, meaning it can affect your sleep-wake cycle and it’s also known that the effects of caffeine only reduce by half in 6-8 hours!
Surely a half-life this strong is going to affect sleep?!
One reason the study may have given such surprising results is due to its reliance on sleep diaries and wrist sensors to collect their data, which are not the most accurate device to measure sleep levels on.
While nicotine and alcohol may have caused more obvious and alarming changes, there’s every chance caffeine was having a slightly stealthier effect.
Is it possible that the subjects’ sleep was being affected by coffee and they didn’t even know it?
Coffee Before Bed: Why You May Not Notice An Effect
A particularly interesting study to pay attention to is one by Henry Ford Hospital and Wayne State College of Medicine in Detroit in 2013, which concluded that caffeine consumption can affect sleep when ingested minutes, three hours and even six hours before bedtime.
Although not a large study group, the 16 participants in the trial were very carefully selected, with no history of sleep ailment and all in good physical health.
The research found that just 115mg of caffeine consumed six hours before bed could reduce sleep by an average of 41 minutes and that participants also took twice as long to fall asleep than when given a placebo.
Its other findings might also explain why the 2019 study had such a different outcome.
Whereas the 2019 research relied purely on sleep diaries and a wrist sensor, the 2013 research used sleep diaries and a more accurate sleep headband, which monitored total sleep time, persistent sleep, wake time during the night and overall sleep efficiency.
And the really interesting results were found when comparing their self-reported diary effects with the actual recorded sleep data.
Amazingly, they found that despite caffeine levels showing obvious effects on quality of sleep, most of the subjects did not record any problems in their sleep diaries the further back the coffee was ingested, especially when it was six hours previously.
The researchers theorised this was because participants were less likely to notice a broken, less deep sleep than the more obvious disturbance of being unable to get to sleep at all.
It stands to reason then that those night owls who go to bed after 12 probably wouldn’t even notice the effects of an 8 pm espresso.
This helps explain the 2019 study a little more, as although these people’s sleep was almost definitely being affected in some way by their caffeine intake, the effects were potentially not strong enough to knowingly disturb them or show massive drops of sleep quality in the data.
But if you don’t notice it… Does that mean it’s okay?
Coffee Before Bed: Why You Probably Still Shouldn’t Do It
Unfortunately, it’s basic science that caffeine and therefore coffee can potentially harm your sleep when drunk in the late hours, as there’s no way your body can reject its stimulant effects.
Nevertheless, we now know from the aforementioned studies that although it does have an effect, whether you feel its impact or not can differ from person to person.
Every person reacts differently to caffeine, with some people having naturally higher tolerances and others building one up over time through frequent coffee consumption.
Yes, we’re sorry to say it jitterbugs, but some people just can drink coffee in the evening without it keeping them up all night!
However, that doesn’t mean it isn’t having a negative effect.
If you are suffering from insomnia and suspect it’s late-night coffee, it’s obvious you should cut back, but even if you’re not noticing any issues with sleep specifically, it might still be wise to give up on late-night brews.
When going to sleep with large amounts of caffeine in your body, even if you nod off, it can hamper your body’s ability to achieve deep, restorative sleep as shown in the 2013 study.
So while you might awaken thinking everything’s fine, there’s a reason why you suddenly crash and desperately need a coffee to wake you back up around mid-day – you’re getting sleep sure, but it’s not good quality sleep.
Contrary to what Dr Stanley said earlier, people also often find that their caffeine sensitivity increases with age, so if you’re starting to suffer from insomnia out of the blue after a big birthday, it may well, in fact, be those two black coffees before bed you’ve been drinking without issue for years!
Ultimately though, if you enjoy an evening coffee and are pretty sure you’re feeling no effects, you may just have an incredibly high tolerance and be one of the lucky ones.
We definitely don’t recommend anyone taking it up, but if night time Nespresso is already part of your daily routine and seemingly doing no harm, who are we to stop you!?
What Time Should I Stop Drinking Coffee?
For those who don’t have as great tolerance and spend your nights staring at the alarm clock after an afternoon coffee shop trip, it’s not a bad idea to set yourself a coffee clock-off period.
Given that 6-8 hours is just the half-life of coffee’s stimulant effects, it’s probably wise to try and keep away from java 6-8 hours before bedtime at a minimum!
On average, people in the UK hit the hay between 10-11 pm at night meaning if you make your cut off point for coffee around 2 pm, it’s going to have much less of a detrimental effect.
Better yet, if you have a later bedtime or can reduce intake to exclusively before 12pm, you’re pretty much guaranteed to suffer no ill effects once under the duvet.