Blocking these receptors leads to a more wakeful state that can increase focus, said Dr. Oliver Grundmann, who studies how plants affect the brain at the University of Florida.

Still, midnight drives with a wakeful infant aren’t quite the same test he faces in his latest TV role.

More wakeful than he’d been, he realized that winter had become less cold, and he bestirred himself to be up and around.

Identifying processes in the brain that underlie sleep-deprived boosting of mood could lead to therapies that are less burdensome than enduring a wakeful night.

There was something else, something inherently evil had drifted into my wakeful consciousness, a bad dream of some kind—a warning, perhaps.