What’s the difference between lack of sleep and sleep deprivation? Sleep deprivation is when a person does not get enough sleep to feel awake and alert, the result of lack of sleep. In general, young adults and children are more vulnerable to a shortage of sleep, than adults. But how little sleep is needed to feel sleep deprived varies from person to person. Occasional sleep interruptions are normally nothing to worry about. But can lead to more serious effects if they persist for a longer time. Sleep loss alters the normal functioning of attention and can lead to the inability to focus. Deadly when, for example, driving a car. making sure you get enough high-quality sleep is crucial to feeling good, and to staying safe.