No one can argue with the fact that people need to sleep. Studies have linked a lack of sleep to everything from disruptions in the immune system to cognitive deficits to loss of weight control. Psychiatric problems have also been linked to long-term sleep deprivation. There have been many researches which can prove that sleep deprivation and psychological disorders are closely connected.

Psychiatric disorders are the leading cause of insomnia, the medical condition when a person loses the ability to have a good night's sleep. Studies have also proven that sleep and psychiatric disorders such as schizophrenia and depression are closely related. Similarly, people with psychiatric disorders have other sleep problems, including sleepiness during the day, fatigue, and nightmares. Lack of sleep can also cause psychiatric problems such as paranoia and hallucinations. Difficulties with sleep can make psychiatric disorders worse by making the person confused or frustrated, as well as more sensitive to pain and other medical problems.

People who are depressed have a tendency to wake up early, and then, they find it hard to sleep again. This can make their depression worse, since the amount of sleep a person gets has an effect on his or her illness and disposition. People who don't have a psychiatric illness but suffer from insomnia are more likely to develop a disorder like depression later in their life.

It's no secret that the sleep-deprived are usually grumpy, miserable, and not much fun to be with. One of the functions of sleep is to reset and replenish the emotional capacity of our brain circuits so we can approach the day's emotional challenges in appropriate ways. If one doesn't get enough sleep, he or she will be making irrational choices.

Doctors and sociologists agree that Americans are among the most sleep-deprived people in the world. According to a 2005 poll conducted by the National Sleep Foundation, about 40 percent of Americans get less than seven hours of sleep at night and 75 percent reported having some sort of sleep disorder one or two nights a week.

According to the research, lack of sleep can lead to a loss of concentration and memory and it can make people more sluggish and exhibit slower and less coordinated motor skills. Lack of sleep also weakens the immune system while abnormally increasing activity in some parts of the brain --- a factor that is related to a variety of psychiatric disorders. If one does not get enough sleep, chances of developing a psychiatric disorder are much greater, at least, based on research from Harvard Medical School and the University of California in Berkeley (UCLA). The said research indicated that brain scans taken from volunteers show that the sleep-deprived brain becomes tired and abnormally emotional. The Harvard and UCLA researchers had 35 volunteer-participants who did not sleep for 35 hours. They discovered enormous activity in parts of the brain when they looked at pictures aimed at making them sad or angry. The researchers, with the aid of fMRI (functional magnetic resonance imaging), were able to examine the blood flow in the brains of the volunteers in real time, after and during sleep deprivation. The technology reveals which parts of the brain are experiencing the most activity.

After a long stretch without sleep the participants were asked to look at images that were designed to trigger an emotional response. The scientists further explained that the amygdala showed 60% higher reaction to the images compared to people who are not sleep-deprived. The amygdala is a part of the brain which is linked to emotional reactions.

But sleep experts are hopeful that more study could lead to refined options for treating not just sleep disorders but psychiatric problems such as depression and anxiety. This means that a sleepless night can cause them to overreact to emotional challenges that they would otherwise be able to tolerate with no trouble.