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.
In this article. Sleep apnea is a serious sleep disorder that occurs when a person's breathing is interrupted during sleep. People with untreated sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times. This means the brain -- and the rest of the body -- may not get enough oxygen.