In contrast, Manser says, a person's passive vocabulary consists of the words whose meanings they knowâso that they do not have to look the words up in a dictionaryâbut which they would not necessarily use in ordinary conversation or writing (The Penguin Writer's Manual, 2004).
Sleep Apnea, Night Terrors, and Nightmares. Sleep apnea may also be to blame for your nightmares. During sleep apnea, your brain senses the low oxygen and realizes that you are under a very real threatâyou are being choked or smothered by your own bodyâand if nothing is done you will die.
Sleep apnea results when soft tissue in the back of the airway collapses and blocks it, causing an interruption in breathing that lasts 10 seconds or more. Victims of moderate to severe forms can suffer 20 to 30 such episodes per hour all night without realizing they are being disturbed.