Why Juggling Screens Leaves You Foggy — And What Actually Helps

Switching constantly between a phone, a laptop and a television does not just fragment your attention — it burns through the brain's fuel supply, journalist Manoush Zomorodi told NPR's Life Kit.

"Every time you switch a task, you use glucose," said Zomorodi, host of the TED Radio Hour. "And every time you use glucose in your brain, you're burning through a finite amount of it, as well as the oxygen it takes to burn it." The brain clears the carbon dioxide left behind, she said, but past a certain point the byproducts build up. "So that is when you start to feel tired and foggy, mentally fatigued, maybe even feel it in your body."

Zomorodi is a co-author, with behavioral medicine scientist Keith Diaz, of Body Electric: The Hidden Health Costs of the Digital Age and New Science to Reclaim Your Well-Being, published in May. The book examines the physiological effects of digital life and offers evidence-backed strategies to counter them. Zomorodi also hosted the NPR podcast Body Electric.

She calls the compulsion to keep consuming more information "infomania." "Sure, I could read all these things, but then do I remember what I've read?" she said. "My brain is not infinite with RAM."

Asked about symptoms, Zomorodi pointed to responses gathered for a podcast: eye twitches, trouble falling asleep after long stretches of screen time, and an inability to concentrate.

The habit is self-sustaining, she said, citing research by Gloria Mark of the University of California, Irvine, on how people shift attention. After an hour of hopping between X, Instagram and email, Zomorodi said, a person will begin interrupting themselves even when nothing external demands it. "It takes time to get into the rhythm that is required for reading something carefully and cautiously."

Her recommendations are blunt. Single-task: one thing at a time, all the way through, then a break, then the next task. Make the break physical rather than digital. "Not take a break on your phone, because that's burning glucose again," she said. "Literally get up and walk around the room." Moving muscles pumps more blood, oxygen and glucose to the brain — which is also why, she said, the afternoon craving for chocolate makes sense.

For self-interruption, she advises deciding in advance how you will respond, "so your brain reaches for that instead of the phone." And she suggests treating yourself as "an information athlete with information goals": decide what you want from time on the phone, and stop once you have it.