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.
Oxygen derived from the air is delivered via the bloodstream to the body organs and tissues. A low blood oxygen level, or hypoxemia, can occur due to reduced environmental oxygen or a problem affecting the respiratory or circulatory system. In many people with hypoxemia, several factors contribute to the low blood oxygen level. Video of the Day