【填空题】

Inadequate rest means a weaker ______  system, laying the body open to a whole ______  of illnesses. On the average a man needs seven hours of sleep a day and a woman seven and a ______  hours. Six hours of ______ sleep is better than ten hours of ______ and turning, however. People who sleep less than six hours a night are______ for an early death.
 Some people______ that they can get by with little sleep when necessary. But experts think these people are______  themselves.
Between sleep______ and fatal accidents there is an obvious______ . People who get ______  sleep or poor quality sleep have a higher risk of ______  on the road. They are more likely to fall asleep at the ______  and kill people or get killed. Professional drivers and______  workers are most likely to take the ______ . The performance at work also ______  because of sleep deprivation.
The pressures of work deprive people of sleep. To make it up, they try to______  catnaps. But experts are a little______  about the benefits of catnapping. They tell us that the catnap can never be a______  for proper sleep. For victims of ______ , catnapping in the day is the worst thing they can possibly do.