Humans need sleep because it is an essential process to maintain health. Sleep is necessary for cognitive functions, such as memory, emotions and learning, as well as physical functions, such as cardiovascular performance and metabolism.
Sleep plays an important role in overall physical health. Sleep deprivation can cause or accelerate many health problems and even has the potential to cause death. During sleep, the body releases certain hormones that regulate functions like metabolism. A lack of sleep can increase appetite and affect the body's ability to store carbohydrates, leading to weight gain.
Sleep is also required to tend to muscle repairs. A lack of sleep increases the amount of stress hormones in the body. As a result, hypertension and irregular heartbeats may occur. Sleep deprivation can also weaken the immune system, resulting in increased chances of infections and diseases.
Sleep has a major impact on brain function. A lack of sleep can cause symptoms like forgetfulness and irritability. Chronic sleep deprivation can impair decision making and can also distort senses, such as the sense of time, and memory. Sleeping allows the brain to filter and store memories in a process known as memory consolidation. Sleep also helps regulate and process emotions.
The recommended amount of sleep is at least 8 hours per night. However, some people require more while others can function on significantly less without adverse symptoms.