Over the past few years, I’ve been devoting less time to reading books. My reading time has gone to magazines, articles, and other short-form journalism. I wasn’t happy about this, but I didn’t do much to change it.

A few weeks ago, we visited the beautiful Central Library here in Seattle to get my daughter her first library card. When I inquired about my card, the librarian said it was long expired, and issued me a new one.

Curious about Seattle Public Library’s online collection, I checked out a couple of non-fiction books that I’ve been meaning to read (Business Adventures which Bill Gates recommended a couple of years ago, and The Hard Thing About Hard Things which more than one person recommended to me at work).

When I checked the electronic books out and downloaded them to my phone, I saw that I had 21 days to read them before they were automatically returned. 21 days! And then they’re gone! I had a deadline.

I read these books during my commute. I read them at night before bed. I even check out the audiobook versions so I can listen to them being read to me during chores at home. The result: I’m reading more books now than I have in the past few years. This is the power of deadlines: it provides clarity in priorities, and forces you to decide what’s really important to hit the date.

However, there are dark sides to deadlines, too.

The dark sides

When you apply time pressure on tasks, creative thinking can suffer. Worse, a Harvard Business School study found that people under time pressure think they’re being more creative when they’re actually less creative. Even worse, there seems to be a hangover to the lull in creativity that can last for a few days after the time crunch.

Why is this? The root cause appears to be lack of focus. Here’s what the study says about people who lacked time to focus during time-pressured days:

But when this protected focus was missing on time-pressured days—and it very often was—people felt more like they were on a treadmill. On these days, our diarists reported a more extreme level of time pressure even though they were not working more hours, and they felt much more distracted. When recording the number of different activities they performed, they were likely to use words like “several,” “many,” and “too numerous to count.” They were pulled in too many directions, unable to focus on a single activity for any significant period of time. One diarist, paraphrasing the oft-repeated lament, said: “The faster I run, the behinder I get.”

Cramming work at the last minute can also result in lower-quality work. A study from Syracuse University showed that patent applications clustered near the deadlines, and those that were completed at the deadline were both more complex and of lower quality.

And, too many aggressive deadlines with no end in sight can create a condition of chronic stress on the mind and body, which can lead to burnout.

Use deadlines wisely

Deadlines are of course not inherently bad. Work can fill all available time, and if there is no bound to that time, you and your team may never get a plan together to deliver something of value. The trick is to use deadlines in a productive way.

As for my library reading, I’ve decided to check out only one or two books at a time. After all, I don’t want my library checkouts to mean I never read magazines and articles anymore!

Remember to have a good reason for each deadline you communicate to your team. Make sure the deadline is achievable. And, above all, make sure your team uses the deadline as a way to focus on what is most important, instead of trying to do too many things at once and doing them all poorly.