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 can be treated with dental devices, surgery, or a continuous positive airway pressure (CPAP) machineâa mask worn at night to help keep airways open. Previous research has shown that sleep apnea can contribute to high blood pressure, heart attack, stroke, automobile accidents, and other health concerns.