I like to tell people that the night before I stopped sleeping, I slept. Not only that: I slept well. Years ago, a boyfriend of mine, even-keeled during the day but restless at night, told me how hard it was to toss and turn while I instantly sank into the crude, Neanderthal slumber of the dead. When I found a magazine job that allowed me to keep night-owl hours, my rhythms had the precision of an atomic clock. I fell asleep at 1 a.m. I woke up at 9 a.m. One to nine, one to nine, one to nine, night after night, day after day. As most researchers can tell you, this click track is essential to health outcomes: One needs consistent bedtimes and wake-up times. And I had them, naturally; when I lost my alarm clock, I didn’t bother getting another until I had an early-morning flight to catch.

Then, one night maybe two months before I turned 29, that vaguening sense that normal sleepers have when they’re lying in bed—their thoughts pixelating into surreal images, their mind listing toward unconsciousness—completely deserted me.