Coffee is a daily ritual for millions of people around the world. In fact, caffeine is the most widely consumed psychoactive drug on the planet. While that morning cup can feel essential, drinking coffee too late in the day can seriously interfere with your sleep and throw off your body’s natural rhythm.
Scientists have long been fascinated by coffee and its
effects on the brain. One major reason is its
impact on the body’s internal
clock, known as the circadian rhythm. This clock regulates biological patterns
such as when we feel alert and when we feel sleepy. When caffeine enters the
picture at the wrong time, that clock can be disrupted.
One study followed 12 participants and found that “caffeine
consumed 0, 3, and 6 hours before bedtime diminished sleep quality.” Using
sleep monitors, researchers measured total sleep time and sleep efficiency,
which is the percentage of time spent asleep while in bed. The study showed
that caffeine consumed even six hours before bedtime had significant negative
effects on sleep.
Another research study found that drinking a double
espresso just three hours before bedtime delayed the production of melatonin
which is the hormone that helps signal to your body that it’s time to sleep. It
delayed it by about 40 minutes. This delay makes it much harder to fall asleep,
even if you feel tired.
What Happens When You Drink Coffee Too Late?
In order to understand why nighttime coffee causes such
problems, it helps to look at what’s happening inside your body.
Your body is made up of trillions of cells, and each one
has its own circadian rhythm. Think of these rhythms like part of a tiny
machine. Throughout the day, they work together to keep you alert. When evening
approaches and the sun goes down, those parts begin to slow, preparing your
body for rest.
Now imagine you’re out to dinner with friends in the
evening and decide to order a coffee. While you’re enjoying the conversation,
caffeine is quietly entering your system and as the coffee spreads through your
body, it reaches each cell and wakes it back up. The parts of the machine that
were slowing down suddenly speed up again. For the next few hours, your body
behaves as if it’s still daytime so you are alert, energized, and focused.
Later that night, you get home, climb into bed, and
expect to fall asleep but your cells aren’t ready. Even if you do manage to
sleep, it’s unlikely to be deep or restoring sleep. Instead of waking up
refreshed, you could feel groggy, unfocused, and tired the next morning.
The Caffeine Cycle
This is how many people fall into a cycle of poor sleep because
caffeine disrupted your sleep the night before, so you wake up exhausted. So, to
cope, you drink more coffee the next day. That extra caffeine can push your
intake later into the afternoon or evening, once again interfering with sleep. Over
time, this cycle can lead to chronic fatigue, reduced concentration, and an
increasing dependence on caffeine just to get through the day.
it’s not that coffee is bad. If you have it earlier in the
day, it can improve alertness, mood, and productivity. It’s all in the timing. If
you want better sleep and more natural energy during the day, consider stopping
caffeine intake in the afternoon or early evening. This gives your body time to
wind down allowing your internal clock to function properly. Sometimes, the
best way to feel more awake tomorrow is to skip that cup of coffee tonight.
