The Weird Reason Why Your Coffee Could Actually Be Making You Tired

I thought I was alone in experiencing a post-caffeine slump, rather than an after-coffee buzz. But a recent video by Dr. Karan Raj, known for debunking medical myths on TikTok, dispelled my delusion (hate when that happens). 

The doctor began by stitching a video in which a user showed how rundown they get after energy drinks. “If caffeine makes you feel tired, it might be because of a software glitch in your caffeine gene,” the doctor began. 

“Broadly speaking, people can be fast or slow caffeine metabolisers. And it all depends [on] if you have the fast or slow liver enzyme CYP1A2,” he added. 

Here’s what he means: 

C1-what now?

CYP1A2, the enzyme Dr. Raj talks about in the video, is a metabolising enzyme you usually see in the liver. 

“Several variants of CYP1A2 have been reported; some of them can show an impact on the metabolism of various drugs. These variants show nearly 40% variability in the liver, while 60% variation in caffeine metabolism,” Science Direct says.

And “depending on your metabolism, it could be anywhere from two to eight hours to remove half of the caffeine,” Dr. Raj explains. 

“Caffeine keeps you alert by blocking adenosine receptors,” he points out.

“People with a fast-metabolising mutation break down caffeine more quickly, so those adenosine receptors free up more quickly, allowing the sleep-inducing chemical adenosine to bind and make you feel more tired than a slow metaboliser.” 

I knew I was just working harder than perky post-coffee people. 

The doctor adds that if you drink a lot of coffee, your body can essentially reprogram itself and compensate by producing “even more adenosine receptors in your brain.” 

It might be annoying during your morning slump, but it does this “to regulate your sleep cycle so you don’t glitch out,” Dr. Raj says.

So, a speedy CYP1A2 enzyme and drinking a lot of java can both cause your post-caffeine energy dip (life is so unfair).