In some ways a person deprived of this much sleep is awake, but in other ways, their behavior is not like that of true wakefulness. In one experiment, after about 40 hours of sleep deprivation all participants shoed some psychotic symptoms, though the severity of these symptoms varied considerably across participants. After about 40 hours of sleep deprivation, the will of a person to stay awake lapses in its effectiveness. An individual must be continually monitored to ensure that sleep does not occur. One nearly universal aspect of sleep deprivation in humans and animals is that it becomes more difficult to keep an organism awake as the period of sleep deprivation lengthens.
Puppies become progressively more difficult to keep awake the longer they are sleep deprived.
It becomes harder to keep puppies awake in periods of rest, while it is somewhat easier in periods of physical inactivity, or when the attention of the dog was captivated. However, after 3 or 4 days of deprivation, puppies showed a loss of interest in the environment, and made continual attempts to sleep. Human subjects are capable of lying awake in bed during the first night of sleep deprivation. During and after the second night, it becomes virtually impossible to keep a sleep-deprived person awake if he or she is in bed. Because of this, one of the challenges that experimenters researching sleep deprivation initially faced was to be able to separate any observable effects as owing to sleep deprivation or the activity that was necessary to produce the sleep deprivation.