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.
Three-fourths of adults whose sleep is affected by stress or anxiety say that their sleep problems have also increased their stress and anxiety: 54 percent say that stress or anxiety increased their anxiety about falling asleep at night, and 52 percent of men and 42 percent of women reported it affected their ability to remain focused the next day.