It’s widely known that caffeine keeps people awake, but researchers have recently found yet another way that caffeine affects sleep. Scientists have long known that caffeine affects the brain by blocking adenosine, increasing adrenaline and delaying dopamine reabsorption. Last September, a study found that caffeine also interferes with circadian rhythms. If you like to sleep at night and wake up on time in the morning, these findings may help you enjoy coffee without sacrificing precious zzzzz’s.
Your Circadian Clock Keeps Time for Your Cells
Your circadian clock is an internal clock that keeps your body’s cells on schedule. It’s incorporated into many muscle cells and can be found in everything from your liver to your brain. According to scientists who study this clock, it’s much more advanced than a simple sleep-wake switch, and irregularities in it can lead to complexities. In general, it keeps your body in tune with the different times of the day and night.
Caffeine Affects Your Circadian Clock And Your Sleep
For a while now, researchers have known that caffeine affects the circadian clocks of mold, algae and sea snails, but no one studied how it impacted humans’ circadian clocks until 2015. A study published in the online journal Science Translational Medicine in September of last year was the first study to specifically examine this.
The study looked at melatonin levels, which are an indicator of sleepiness, in people over a period of 49 days. Typically, there is a rush of melatonin at the time that people go to sleep. When participants had a doppio (double shot espresso) 3 hours before their bedtime, the rush was delayed by 40 minutes.
In addition to making it harder to fall asleep, having a doppio 3 hours before bed also made it more difficult to wake up the next morning. The study found that participants had a significantly harder time waking up on time when their melatonin levels were delayed.
The study did not examine other coffee beverages, but it can be assumed that drinking any non-decaf coffee would disrupt falling asleep and waking up. According to the Mayo Clinic, a two-ounce espresso (doppio) would have between 94 and 150 milligrams of caffeine, which is similar to 8 ounces of brewed coffee (95 to 200 milligrams of caffeine), and the same as lattes or cappuccinos that have two shots.
Switch to Decaf 5 Hours Before Bed
The study didn’t investigate drinking coffee at other times of the day, so there are no official findings on what time of day you should stop drinking coffee. A scientist familiar with the study’s findings, however, suggested that cutting out caffeinated coffee 5 or 6 hours before you go to sleep would likely eliminate the effect on melatonin levels.
If you want to sleep soundly at night and wake up on time in the morning, try switching to decaf 5 hours before you go to sleep. That leaves plenty of time for drinking regular coffee, and it shouldn’t interfere with your circadian rhythms.
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