Sleep is an essential requirement for sustaining human life. Nobody is entirely sure just how sleep works or what the body does while you're out, but it is known that depriving yourself of a full night's sleep can have unpleasant side effects. Sleep deprivation, sadly, is a growing problem in the modern world. Whether it is their schedule, the stress from work, or chronic pain, people are finding it more difficult to get a full night's (or day's) rest. The vast majority of people don't consider this to be a major problem, but that is only because they don't seem to fully grasp the potential dangers associated with a lack of sleep. Being deprived of sleep long enough can actually be fatal. But surely, even short-term deprivation can have consequences on the mind and body.
Decreased alertness and reflexes are the first signs that someone hasn't been getting enough sleep. As side effects go, most people don't really pay much attention to this. For the most part, people who experience this problem tend to think that a couple of cups of coffee throughout the day can compensate. However, sluggish and slow behavior can have consequences on one's personal and professional performance, even if caffeine is taken to compensate. The impaired environmental awareness and the reduced ability to react to things quickly enough is just the first of many potential side effects.
Sleep deprivation can be very hazardous to a person's mental health, particularly if the lack of sleep is chronic. Psychiatric conditions are among the potential consequences of not getting enough sleep, with conditions such as depression and anxiety often being used as examples. Cognitive abilities and perception are also impaired, such that some people who haven't gotten enough sleep are reported to have experienced brief psychotic episodes. Emotional stability may also suffer if the lack of sleep is accompanied by other emotional factors, playing on the brain's already impaired ability to properly process stimuli from the environment and from other people.
According to studies, mammals that are rendered unable to sleep for prolonged periods tend to die from the loss of the ability to regulate their body temperature. While this has not been tested on humans, it is reasonable to assume that the same would occur if a person were to be prevented from sleeping for three weeks. A lack of sleep in connection with fatal familial insomnia can cause rapid degeneration of brain cells, though it is uncertain if fatalities are directly caused by the sleep deprivation or if it was caused by a related problem.
The immune system can also be impaired by a lack of sleep, making a person more susceptible to infection and disease. The cardiovascular system, which is believed to go into a more relaxed state during sleep, can be taxed during prolonged period without sleep. In some cases, three days without sleep can lead to a heart attack or heart failure. Blood pressure has also been known to go up due to lack of sleep, with some cases being reported where the pressure actually doubled. This, combined with the effects on mood and temperament, can do serious damage to a person's relationships.
Indeed, losing sleep is more than just being drowsy the morning after. If left unaddressed for such a long period of time, it could worsen and lead to the loss of not only sleep --- but of one's mind, as well.