As previously stated, a lack of sleep can lead to lower mental attentiveness and cognitive performance. Furthermore, sleep loss frequently leads to depression-like symptoms. These consequences can develop as a result of cumulative sleep debt or as a result of more acute sleep deprivation. Acute sleep deprivation is defined as the absence of sleep for one night or less, while cumulative sleep debt occurs when an individual has been without sleep for several days or weeks. The most apparent effect of sleep deprivation is reduced alertness. Individuals who have not gotten enough sleep will generally appear more tired and sluggish than those who have had a good night's sleep. Sleep deprivation also increases the risk of making mistakes in judgment and reasoning tasks, have difficulties focusing attention, and experience increased levels of anxiety. Over time, sleep deprivation can have serious negative effects on your mind and body. It has been shown to increase the risk of diabetes, heart disease, and cancer, as well as increasing the likelihood of having a stroke. Sleep deprivation has also been linked to increased aggression and violence toward others. Finally, sleep deprivation can lead to depression. Many people assume that depressed individuals are just "down" because they are feeling sad about something. However, someone who is depressed cannot be relied upon to get their necessary amount of sleep. Because of this, they will continue to feel tired yet remain physically active during sleep hours.