Flexible work is not going anywhere, but its positive effects are less of a sure thing. The 9-5 work schedule is deeply woven into our social fabric, and when we work outside of it, we’re a lot more likely to wonder what else we could be doing instead. Flexible work can definitely improve productivity and the employee experience, but we have to be very intentional in communicating and reminding people of why they’re doing it.

Flexible work is not going anywhere, but making the most of flexibility is not going to be a walk in the park. A recent study from researchers at Cornell and London Business School found that “Working at non-standard times such as weekends or holidays significantly reduced people’s intrinsic motivation, making work less motivating and enjoyable.”

Wait… isn’t that what everyone has been asking for?

It is, and it’s still what employees want. But as it turns out, the 9-5 work week is deeply baked into our society. From some of our earliest school experiences onward, we grow up with a clear sense of the norms around when people work and when they don’t. The same way a child is less excited doing homework on a Sunday night or during Spring Break, employees working on a weekend or after traditional work hours are much more likely to ponder what they’re missing out on. This doesn’t mean that person doesn’t want flexible work; statistically, they probably do. It’s a reminder, rather, that breaking social norms is a tricky thing. Sometimes doing so motivates you, other times it saps you of motivation — depending on the time of day.

Luckily, the study also supports the idea that if we’re intentional in how we frame and put flexible schedules into practice, we can protect a lot of that motivation. If employees actively remember the benefits of why they’re working late, they’re more likely to enjoy it.

So what can we do? For us, the most important takeaway is that we need to actively communicate why employees are working on flexible schedules — for instance, because your company trusts people to work at the times that suit them best, or because by working on a Sunday night, they will be able to sleep in Monday morning. One way to remind people of these different norms is simply to encourage employees working during the same nontraditional work hours to connect with one another. When we’re less isolated doing something against the grain, we’re more likely to stay in touch with the positive whys of our own behavior.

Which gets to another crucial consideration. To tap into flexible work’s benefits, you need to make sure that the working norms of your company really do support flexible work, as opposed to just more work. If an employee works untraditional hours and then feels like she still needs to be on Slack or on meetings throughout the regular day, she is not benefitting from flexibility. Rather, she is having her work-life boundary blurred, in a recipe as classic as any for burnout.

Ultimately, however, the biggest takeaway of this study should be for people managers. It’s imperative that managers stay aware of this reality as they check in on, protect and advocate for their people. As leaders, our approach to flexible work should not be one of blind faith, but rather one of cautious optimism. We need to make sure flexibility really is benefitting our people, and be ready to adjust to ensure it works the same in practice as in theory.