38,124 employees
A Meta-Analysis on Antecedents and Outcomes of Detachment from Work
Wendsche & Lohmann-Haislah, 2017
Across 86 publications, employees who were better able to mentally disconnect from work tended to report less exhaustion, better sleep, and greater wellbeing. It also found positive associations with task performance, though that shouldn't be read as proof that switching off automatically improves productivity.
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