Multitasking Is No Longer Something to Boast About

This article originally appeared on Entrepreneur.

What are you doing while you read this? Are you dipping into your email while texting, reading tweets and partly listening at a meeting? Do you have your mobile phone, a desk phone, a tablet and a laptop all on the go at once?

Probably. We all tend to do it, some more often than others. After all, multitasking is the sign of a highly effective and efficient mind—right?

Wrong.

It’s time for a reminder about the power of singletasking.

It’s not you, it’s your brain.

Doing several things at once makes you feel very busy, but your body and mind simply aren’t designed to work that way. Switching between tasks actually reduces your proficiency and efficiency. This could be due to how blood flows through our brains. Nerve fibers store very little energy, so when we think, problem-solve or create memories, our gray matter demands a steady supply of oxygen, glucose and nutrients.

Here’s the problem: If you simultaneously activate several parts of your brain, it’s smart enough to distribute incoming blood to those different areas. This reduces the volume and quality of the fuel you can devote to any mental task. Imagine a firefighter trying to put out three house fires at once by spraying a hose back and forth over them all. There’s never enough water in one place to extinguish the blaze.

Multitasking can temporarily lower your IQ.

Some of the earliest research in the field comes from the United Kingdom. One of the most-cited is a 2005 study conducted by Dr. Glenn Wilson, then a psychiatrist at King’s College, London University. Wilson found that workers who are distracted by phone calls, emails and text messages suffer a greater loss of IQ than a person smoking marijuana. His approach included 80 clinical trials, each time monitoring workers’ IQ throughout the day. Wilson’s work revealed that multitasking could temporarily decrease IQ by an average of 10 points (15 for men and 5 for women)—equivalent to missing a whole night’s sleep.

The solution is to simplify our work periods. Remember: Blood flow to the brain can’t deliver optimum supply to all part of the brain at once. We can activate only targeted, smaller parts of the brain at any given moment.

For more on productivity, watch this Fortune video:

Decide what’s most important.

Protect time during each work day so you can minimize distractions and perform to your full potential. Single-tasking demands that we start with the most important task. To accomplish more, we must understand that “important” and “urgent” are not the same. Serious responsibilities might not call for your attention in the form of an email alert or ringing phone, but they require your concentrated focus just the same.

Once you’ve determined which item on your to-do list is most important, work on it exclusively until it’s completed or you come up against the deadline. Then, move on to whatever’s next.

Of course, this means managing your time and controlling when you’ll respond to emails or return voice messages. I recommend avoiding email first thing in the morning so you don’t get derailed by something that’s urgent but not important. Set aside specific times of day—two or three blocks—when you’ll do nothing but respond to these inquiries.

Get started today.

Try dedicating one 60- to 90-minute block of time each day to the highest-priority tasks. Discipline yourself to work in a distraction-free manner for the full time period. Resist the urge to fire back a text message. Keep in mind that habits can be hard to break, and you might not realize you’re in a rut.

Gradually build more singletasking sessions into your daily schedule. You’ll feel more focused and productive as you improve your performance—and your mental health. Small, incremental changes can lead to improvements you didn’t think possible.

Give the science a chance. Work on becoming a singletasker so both your brain and your business stay sharp.