Find Out What Happens When You Give Up Sleep For Days

— -- Ever wonder just what effect pulling an all-nighter can have on your body? After talking to a few experts, it turns out plenty.

Sleep is a key part of any healthy lifestyle and today Dan Childs, head of the ABC News Medical Unit, will attempt to show how important it is to get some shut eye by doing the exact opposite and staying awake for 40 hours.

Not sleeping can wreak havoc with your body in multiple ways including weakening your immune system and affecting your cardiovascular system, your cognitive function and even your memory.

The effects can take effect quickly. After just one all-nighter, a person's cognitive ability is so impaired that it's comparable to having a blood-alcohol level of 0.10 percent, according to a 2010 study.

The National Department of Transportation estimates drowsy driving is responsible for 1,550 fatalities and 40,000 nonfatal injuries annually in the United States.

Namni Goel, a sleep expert and associate professor of psychiatry at the University of Pennsylvania, said a lack of sleep has plenty of effects on the body besides fatigue. A sleep-deprived person's hormones will change so that they will crave unhealthy foods.

"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."

Sleep expert Dr. Ilene Rosen explained that memory is also severely impacted by a lack of sleep.

"Short-term memory is definitely affected and something you may have learned or studied right before bed might not be remembered in the morning," she explained.

Rosen said a person will start to show slips in judgement after just 16 hours of wakefulness.

"As you extend past 16 hours you get exponentially worse and worse and worse," she explained.

When people are acutely tired, Rosen said the body will sometimes attempt to grab whatever kind of sleep it can, including "microsleep." In those cases, a person can appear awake, with their eyes open, but actually be sleeping.

"They might have been thinking about nothing [until] something brings them back to focus attention," she explained.

ABC News' JULIE BARZILAY and ADAM RODMAN contributed to this article.