As an alternative that links dreams to inherent meaning for the individual, Solms suggested that activation of frontal dopaminergic systems during dreaming, the same pathways that participate in most biologic drives, implies that dreams express latent wishes and drives—a psychoanalytical interpretation expressed by Freud in his book The Interpretation of Dreams.
The Effects of Sleep Deprivation
Deprived of sleep, experimental animals will die within a few weeks, no matter how well they are fed, watered, and housed (Rechtschaffen et al), but whether a similar degree of sleep deprivation leads to death in humans is unknown. Nevertheless, humans beings deprived of sleep do suffer a variety of very unpleasant symptoms quite distinct from the effects of the usual types of insomnia.
Despite many studies of the deleterious emotional and cognitive effects of sleeplessness, we still know little about them. If deprived of sleep (NREM and REM) for periods of 60 to 200 h, human beings experience increasing sleepiness, fatigue, irritability, and difficulty in concentration. Performance of skilled motor activities also deteriorates; if the tasks are of short duration and slow pace, the subject can manage them, but if speed and perseverance are demanded, he cannot. Self-care is neglected, incentive to work wanes, sustained thought and action are interrupted by lapses of attention, judgment is impaired, and the subject becomes decreasingly inclined to communicate. With sustained deprivation, sleepiness becomes increasingly more intense, momentary periods of sleep (“microsleep”) become more intrusive, and the tendency to all types of accidents becomes more marked. Eventually, subjects fail to perceive inner and external experiences accurately and to maintain their orientation. Illusions and hallucinations, mainly visual and tactile ones, intrude into consciousness and become more persistent as the period of sleeplessness is prolonged. This may be a component of the decompensation of individuals with bipolar psychiatric disease, sometimes triggering manic episodes.
Neurologic signs of sleep deprivation include mild and inconstant nystagmus, impairment of saccadic eye movements, loss of accommodation, exophoria, a slight tremor of the hands, ptosis of the eyelids, expressionless face, and thickness of speech, with mispronunciations, and incorrect choice of words. The EEG shows a decrement of alpha waves, and closing of the eyes no longer generates alpha activity. The seizure threshold is reduced, and seizure foci in the EEG may be activated. Rarely and probably only in predisposed persons, loss of sleep provokes a psychotic episode (2 to 3 percent of 350 sleep-deprived patients studied by Tyler); however, many sleep specialists dispute the production of psychosis.
During recovery from prolonged sleep deprivation, the amount of sleep obtained is never equal to the amount lost. This is probably a result of the intrusion of brief sleep periods during the waking state and represents a sizable amount of time if summated (it is virtually impossible to deprive a human being or animal totally of sleep). When falling asleep after a long period of deprivation, the subject rapidly enters N3 (NREM) sleep, which continues for several hours at the expense of N2 and REM sleep. But by the second recovery night, REM sleep rebounds and exceeds that of the predeprivation period. N3 seems to be the most important sleep stage in restoring the altered functions that result from prolonged sleep deprivation.
The effects of differential REM sleep deprivation are more difficult to interpret than the effects of total or near-total deprivation. Some subjects in whom REM sleep is prevented night after night show an increasing tendency to hyperactivity, emotional lability, and impulsivity—a state that has been compared to the heightened activity, excessive appetite, and hypersexuality of animals deprived of REM sleep. However, in humans, monoamine inhibitors are able to completely suppress REM sleep for months to years without obvious harm. Differential deprivation of NREM sleep (N3) leads, instead, to hyporesponsiveness and excessive daytime sleepiness as noted.