There are a number of items that influence the degree to which sleep loss effects behavior.
Age is also an important factor in behavior during sleep deprivation.
Younger rats could withstand more exercise during sleep deprivation than older rats. Motivation is also a decisive factor in an individual s subjective perception of sleepiness. Individuals with high motivation tend to deny sleepiness more than those who have low motivation. They will rate themselves much higher on fatigue than on sleepiness, and their self-ratings of sleepiness will be much lower than the rating of sleepiness by an observer. On certain projective tests, including the Thematic Apperception Test , highly motivated sleep deprived subjects will give fewer sleep themes than control subjects.