Sleeping in on Saturday after a few weeks of too little shuteye may feel refreshing, but it can give a false sense of security. New research shows long-term sleep loss cannot be cured that easily. Scientists researched the effects of short- and long-term sleep loss and found that those who suffer long-term sleep loss may function normally soon after waking up, but experience steadily slower reaction times as the day goes by, even if they had tried to catch up the previous night. The research has important safety significances in an increasingly busy society, not just for shift-workers but for the roughly one in six Americans who regularly get six hours or less of sleep a night. "We know that staying awake 24 hours without sleep will affect your performance to do all sorts of things, and this effect equals to drinking too much when driving," said lead researcher Dr. Daniel Cohen of Boston's Brigham and Women's Hospital. But when those who suffer long-term sleep loss become all-nighters, "the harm is increased ten times," Cohen said. The National Institutes of Health says adults need seven hours to nine hours of sleep for good health. Regularly getting too little sleep increases the risk of health problems, including memory impairment and a weakened immune system. More immediately, too little sleep affects reaction times; sleepiness is to blame for car crashes and other accidents. It has critically important complicated and unexpected results for anyone who works "crazy hours" and thinks they are performing fine with a few hours of weeknight sleep, said Harris, director at New York's Montefiore Medical Center. "Don't think you can just _ your sleep on the weekend, because it doesn't work that way," he warned. Which of the following is the immediate effect of long-term sleep loss?
Health problems Immune system Reaction times Memory impairment