The fourth alternative is correct.
Sleep is the moment in which several metabolic processes that are essential for the functioning of our organism occur. While we sleep we can perform all the fundamental repair functions, such as organizing the information collected during the day, repairing cell damage and producing hormones.
Science explains that sleep deprivation can affect our ability to reason and can cause psychic disorders such as anxiety, irritability and even depression. Likewise, sleep deprivation affects our body, causing a feeling of tiredness and exhaustion.
Therefore, all alternatives are correct. Sleep deprivation is dangerous as it affects the functioning of the brain and the body.