• Your looks aren't the only things that take a hit when you go without sleep for too long.
  
  

Sleep Study

• Numerous studies have looked at how sleep deprivation impairs us on a day-to-day basis. One of the most notable is the Huber-Weidman study, according to British psychologist Michael Eysenck in his book "Psychology: An International Perspective." The study found that for the first three nights without sleep, people didn't do well on tedious tasks. On the fourth night, volunteers would have spurts of non-responsiveness called "micro-sleep." By night five, delusions emerged. From night six on, the effects were more disturbing, such as a loss of identity.
  
  

Case Studies

• Some people will do anything for a cause. Peter Tripp, an American disc jockey, stayed up 200 hours in the name of a charity fund-raiser in the 1950s. Teenager Randy Gardner, Eysenck reports, surpassed Tripp's record by staying awake for nearly 270 hours. He suffered intense paranoia, vision problems and speech difficulties.
  
  

Fatal Familial Insomnia

• Though extreme, there are other examples of how going without sleep for long periods of time can harm us. "Fatal familial insomnia" is a rare genetic condition caused by the wasting away of the thalamus, which is responsible for controlling sleep, according to the Merck pharmaceutical company. The onset usually is between ages of 40 and 60. Typically, victims survive only seven months to three years after symptoms start.
  
  

Metabolism

• Besides mental and emotional disturbances, such as phobias and hallucinations, long-term sleep deprivation can impair our ability to process and store carbohydrates and to control vital hormones, according to the University of Chicago Medical Center. In a U-Chicago study, healthy young men underwent 16 nights of erratic and deprived sleep. Their glucose tolerance and endocrine function became so impaired that it was what would be expected in someone much older or in the early stages of diabetes, the researchers found.
  
  

Performance

• The ability to perform on the job or at school also takes a hit, according to the Mayo Clinic. Any tasks involving information processing are impaired. Case in point--driving. Sluggish reaction times make sleepy drivers dangerous. According to the National Highway Safety Administration, drivers falling asleep behind the wheel contribute to more than 1,500 deaths a year and roughly 70,000 injuries.
  
  

Other Disorders

• A number of serious disorders have been linked to chronic sleeplessness. According to the Mayo Clinic these include obesity, high blood pressure and heart disease.