Discrete Mathematics/Functions and relations. This article examines the concepts of the function and the relation. A relation is any association or link between elements of one set, called the domain or (less formally) the set of inputs, and another set, called the range or set of outputs.
Sleep deprivation. Sleep deprivation is the condition of not having enough sleep; it can be either chronic or acute. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight loss or weight gain. It adversely affects the brain and cognitive function.
Causes of Extreme Fatigue. The Most Common Reasons for Excessive Fatigue. Discovering the causes of extreme fatigue can be difficult if you don't know the distinctions between fatigue and sleepiness. Some disorders cause fatigue, others sleepiness, and some disorders cause a mix of these two. The question is: Are you tired, sleepy, or fatigue? In this page you will learn: 1  What is extreme fatigue, compared to sleepiness and tiredness, 2  What causes extreme fatigue, including most common disorders and medication, 3  Useful questionnaire to test your excessive fatigue, 4  How to stop fatigue in a sleep apnea patient.