One reason is that products are often designed in ways that make us act impulsively and against our better judgment. For example, suppose you have a big meeting at work tomorrow. Ideally, you want to spend some time preparing for it in the evening and then get a good night’s rest. But before you can do either, a notification pops up on your phone indicating that a friend tagged you on Facebook. “This will take a minute,” you tell yourself as you click on it. But after logging in, you discover a long feed of posts by friends. A few clicks later, you find yourself watching a YouTube video that one of them shared. As soon as the video ends, YouTube suggests other related and interesting videos. Before you know it, it’s 1:00 a.m., and it’s clear that you will need an all-nighter to get ready for the following morning’s meeting. This has happened to most of us.