Sleep deprivation can have an enormous impact on your health and happiness. Apparently, it can also affect your ability to make split-second decisions, according to a recent study in the journal SLEEP. Researchers at the University of Texas at Austin split 49 West Point cadets into two groups, 21 of whom were deprived of sleep and 28 of whom were well-rested, and tested them on tasks that require quick decisions. According to the study, participants in each group performed the tasks twice, separated by a 24-hour period. Cadets who were sleep-deprived between testing periods saw their accuracy decline by 2.4 percent, and cadets who were well-rested between testing periods improved by 4.3 percent. W. Todd Maddox, one of the researchers, told HealthDay that the type of thinking tested in this study is "critical in situations when soldiers need to make split-second decisions based about whether a potential target is an enemy soldier, a civilian or one of their own." While people vary in their need for sleep, experts agree that for most adults the amount needed to feel one's best is somewhere between seven and nine hours per night.