When I did an overnight sleep study, the sleep specialist said my arousal index—a measure of how many times per hour something was sending me back to a light stage of sleep, and not nearly as sexy as it sounds—was 97. The respiratory therapist told me it was one of the worst numbers he’d seen in his 30 years of doing sleep studies, and he was curious as to how I functioned on a daily basis. I guess I got used to being sleep deprived.