Remote white-collar workers are no longer working just nine-to-five—more and more are logging on and working late into the night. And that worries Satya Nadella, CEO of Microsoft. At the Wharton Future of Work Conference last week, he argued that the onus is on managers to set reasonable expectations for their teams, so nobody feels pressure to answer an email or finish an assignment after dinner.

In an attempt to improve its Teams software to better meet users’ needs, Microsoft researched how often workers log on by tracking their keyboard activity. During a standard workday, productivity typically peaks in the hours before and after lunch. But during the pandemic, researchers found, one in three white-collar workers started hitting a “third peak” of productivity in the late evening hours, between 6 and 10 p.m.

“We think about productivity through collaboration and output metrics, but well-being is one of the most important pieces of productivity,” Nadella said at the conference, as reported by Bloomberg. “We know what stress does to workers. We need to learn the soft skills—good old-fashioned management practices—so people have their well-being taken care of.”

The average workday has expanded by 46 minutes, or 13%, since the pandemic began, according to Microsoft’s Work Trend Index. What’s more, the average Teams user now sends 42% more messages after hours.

For many workers, especially those with kids, it's easier to log on in the evening to get extra work done, Mary Czerwinski, research manager of human understanding and empathy at Microsoft Research, said in the report. “Parents who tend to their children in the afternoon make up for that time by working in the evening. Others optimize newfound work-from-anywhere flexibility by varying their hours. Some just require the extra breathing room at night, away from pings and business calls, to really focus.”

Flexibility has become paramount to workers during the pandemic, and remote work has become the cornerstone of many job postings. Recent data from Future Forum, a research consortium launched by Slack, found that 95% of knowledge workers want to set their own schedules.

This "third peak" phenomenon might be a result of these new flexible schedules. Instead of outright discouraging late-night emails, managers should give employees the space to determine what timing works best just for them—as long as they’re not expecting replies to their own late-night correspondence.

“The 'third peak' should be an available option for people who need it, but the challenge moving forward is, How can we make sure people are not working 24/7?” says Shamsi Iqbal, principal researcher on productivity and intelligence at Microsoft Research and Microsoft Viva Insight. “If people are working all three peaks, that’s a recipe for early burnout.”

Breaks in the action are essential to productivity and well-being, Iqbal says. One way of ensuring this: scheduling late-night emails and instant messages so they don’t hit inboxes until more typical working hours.

“People often send emails at odd hours because they don’t want to lose the thought and they want it captured, but it doesn’t necessarily have to arrive at the recipient’s end right away,” Iqbal says. “Delaying delivery of that email means that we can get the best of both worlds—capturing the thought so that it doesn’t get lost, and making sure that the recipient gets it at a time that is more convenient for them.”