I was in a bad equilibrium last night. I felt a little agitated when I went to bed, which made it a little hard to fall asleep, which made me more agitated, and which made it even harder to sleep… Long story short: I only slept for three hours, and felt like a zombie most of the day.

During my few lucid moments, it occurred to me that my problem was an odd example of what economists call multiple equilibria. There were two stable situations: One in which I felt calm and slept well, and another in which I felt agitated and slept poorly. Usually, of course, multiple equilibria involve multiple people; but any time there is more than one stable configuration, the concept applies.

Another example: Back when I took tests instead of giving them, I usually stayed calm and did well. But occasionally I got very nervous and did poorly. Once you’re nervous, it’s hard to do well; and if you’re not doing well, it only makes you more nervous.

Given the existence of multiple equilibria, what determines which one prevails? Well, if I could fully answer that, I would have slept like a baby. But here’s where I’d start:

1. It’s hard to quickly make big changes. I can nudge my mood, but I can’t instantly calm down when I’m feeling very agitated. If I’m on the border between sleep and insomnia, telling myself, “Calm down, everything will be fine,” usually works. Last night, that just didn’t cut it.

(Here’s a self-serving interpretation, but that doesn’t make it wrong: I’m bad at self-deception. If I tried telling myself stories to make myself feel better, I’d just scoff at myself).

2. Some equilibria are more focal than others. Most nights, it doesn’t even occur to me than I might have trouble sleeping. So I’m in the good equilibrium by default, and it takes an unusually event to raise doubts about what’s going to happen.

Have you got any other intra-personal applications of the multiple equilibria concept? Any thoughts on how to get to the good equilibrium and stay there?