Insomnia // l.h.

in·som·ni·a

/inˈsämnēə/

also known as trouble sleeping, is a sleep disorder in which there is an inability to fall asleep or to stay asleep as long as desired. While the term is sometimes used to describe a disorder demonstrated by polysomnographic or actigraphic evidence of disturbed sleep, this sleep disorder is often practically defined as a positive response to either of two questions: "Do you experience difficulty sleeping?" or "Do you have difficulty falling or staying asleep?

BOOK I