In view of several obvious practical considerations, many general deprivation studies have used animals rather than human beings as experimental subjects. Waking effects routinely observed in these studies have been of deteriorated physiological functioning, sometimes including actual tissue damage. Long-term sleep deprivation in the rat(6 to 33 days)has been shown to result in severe debilitation and death of the experimental animals. This supports the view that sleep serves a vital physiological function.【F1】
There is some suggestion that age is related to sensitivity to the effects of deprivation, younger organisms proving more capable of withstanding the stress than mature ones.
Among human subjects, the champion non-sleeper apparently was a 17-year-old student who voluntarily undertook a 264-hour sleep deprivation experiment. Effects noted during the deprivation period included irritability, blurred vision, slurring of speech, memory lapses, and confusion concerning his identity. No long-term(i. e. , post-recovery)effects were observed on either his personality or his intellect.【F2】
More generally, although brief hallucinations and easily controlled episodes of bizarre behaviour have been observed after five to 10 days of continuous sleep deprivation, these symptoms do not occur in most subjects and thus offer little support to the hypothesis that sleep loss induces psychosis.
In any event, these symptoms rarely persist beyond the period of sleep that follows the period of deprivation. When inappropriate behaviour does persist, it generally seems to be in persons known to have a tendency toward such behaviour. Generally, upon investigation, injury to the nervous system has not been discovered in persons who have been deprived of sleep for many days. This negative result must be understood in the context of the limited duration of these studies and should not be interpreted as indicating that sleep loss is either safe or desirable.【F3】
The short-term effects observed with the student mentioned are typical and are of the sort that, in the absence of the continuous monitoring his vigil received, might well have endangered his health and safety.
【F4】
Other commonly observed behavioral effects during total sleep deprivation include fatigue, inability to concentrate, and visual or tactile illusions and hallucinations. These effects generally become intensified with increased loss of sleep, but they also wax and wane in a cyclic fashion becoming most acute in the early morning hours.
Changes in intellectual performance during moderate sleep loss can, to a certain extent, be compensated for by increased effort and motivation.【F5】
Changes in body chemistry and in workings of the autonomic nervous system sometimes have been noted during deprivation, but it has proved difficult to establish either consistent patterning in such effects or whether they should be attributed to sleep loss per se or to the stress or other incidental features of the deprivation manipulation
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