You are multitasking in an open-plan office because you have two jobs that are often at odds. One is being productive. The other is appearing productive as part

You are multitasking in an open-plan office because you have two jobs that are often at odds. One is being productive. The other is appearing productive as part of what actually matters at work: managing your own social status within the group. Even if you're not aware of it, your brain is dedicating resources to the latter of these jobs. Over 9 hours, that wears you down. You may not notice it. You may attribute your end-of-day fatigue and digestive problems to aging even though you're not actually old.