In mainstream culture the term “insomnia” is used frequently to describe the inability to fall asleep. If you stay up late at night, bleary-eyed because you can’t go to sleep you typically say you have insomnia. You might call it an “attack of insomnia” or “bout of insomnia,” for an isolated sleepless night, or you may describe yourself as an insomniac or that you suffer from insomnia if sleep is a regular rarity in your life.