Microsoft researchers have documented what they call a “triple peak” phenomenon in which workers’ keyboard activity spikes in the morning and afternoon, then a third time around 10 p.m. The tech giant predicts this pattern is here to stay. 

Flexibility can be a trap that fuels our always-on work culture, Fong adds. Instead of powering through a late-afternoon gathering and being done for the day, he often finds himself refreshing his mobile inbox all evening or opening his laptop on Sunday to catch up on messages from colleagues who work whenever.