What could possibly happen if a person has to stay awake for days straight? Experts say and an experiment proves, quite a lot.

Being sleep deprived can affect the body in several ways including weakening of immune system and decreasing levels of alertness and cognitive function.

Dan Childs of the ABC News Medical Unit attempted to add further evidence to the effects of sleep deprivation on the body by staying awake for 40 hours straight, which will be featured on the network's special 40 for 40 Live Event.

Other studies have also been conducted in connection with sleep and sleep deprivation. In a study made by the National Department of Transportation, more than 40,000 injuries result every year in the U.S. due to drowsy driving. Another study in 2010 found that people who are sleep deprived have cognitive functioning so terrible theirs is nearly the same level as drunks.

Sleep experts and associate professor of psychiatry Namni Goel from the University of Pennsylvania said that lack of sleep may also cause people to crave unhealthy foods due to a change in hormones.

"What we've also seen is people tend to eat more...his intake of fatty foods and carbs may go up," Goel said. "If you give him a choice between chips and apple, they'll pick the chips."

Dr. Ilene Rosen, another sleep expert, also found that memory is strongly affected by lack of sleep, particularly short term memory. For example, what students may have studied the night before after pulling an all-nighter may not remember everything they have reviewed the following morning.

Rosen added that a person will have lapses in judgment and may become worse both physically and mentally the longer a person goes without sleep.

She added that when the body reaches a certain point while sleep deprived, it may sometimes try to shut down to whatever form of sleep it can get. At these times, even though a person may appear awake, he or she is actually asleep and may not move or react to anything around them unless stimulated.

"As you extend past 16 hours you get exponentially worse and worse and worse," Rosen said. "They might have been thinking about nothing [until] something brings them back to focus attention."

Sleep is important to the body because it is during sleep that the body both recharges and repairs itself. Children and teenagers need sufficient sleep to facilitate growth and development. Sleep deprivation is also linked to increased risk for heart and kidney diseases as well as diabetes and stroke.