The Dreaming Brain/Mind: A Role in Understanding Complex Mental Disorders?

Abnormalities in the sleep/wake cycle and within sleep itself have extensively been studied in a broad range of psychiatric and neurodegenerative disorders. Despite increasing evidence for a mechanistic overlap between the disruptions of circa-dian timing control and neuropathology, the relationship remains unclear (Wulff et al., 2010). One possible way to address this problem from a psychiatric perspective is to compare the phenomenological correlate of sleep with the waking menta-tion observed in patients. Indeed, so-called " positive " symptoms such as abnormal senso-perceptual experiences or thought processes ranging from ideas of reference to highly structured delusions, share substantial similarities with dream phenomenol-ogy. The same process by which psychotic patients progress from salience attributed to irrelevant stimuli to a new, highly relevant meaning, appears to occur in dreams, where a single hallucinatory image can convey " an immediate emotionally compelling meaning that is not related to the image in any obvious way " (Feinberg, 2011). With the exception of the rare experience of lucidity , the dreamer has no recognition of his objective status, i.e., being asleep and vastly detached from the external environment ; dream images produced uniquely by endogenous neural activity are interpreted as coming from the external world; heightened and often incongruous emotions are coupled with a decrease in ego functions which ultimately leads to instinctual behaviors and severe impairment in reality testing (Hobson, 2009). The striking similarity between these aspects of dreaming and psy-chosis has been observed by most of the funding pioneers of the modern approach to psychopathology. Indeed, it is largely unknown that Emil Kraepelin extensively studied his own dreams with the aim of progressing his understanding of schizophrenic thought disorder (Engels et al., 2003). Recent advances in neuroscience have led few contemporary researchers to bind these complex phenomena, with electrophysi-ological, neurochemical, and cerebrofunc-tional data now pointing to shared patterns across dreaming and psychotic experiences (Hobson, 2004; Gottesmann, 2006). One relevant issue in the scientific study of dreams is bound to the limits of our current understanding of cerebral activation patterns across different stages of sleep. Despite early observations binding dreams to REM sleep physiology, it is now widely accepted that dreams occur across all stages (Nir and Tononi, 2010). However, mental activity across sleep does differ, ranging from simple thought-like experiences to full-blown hallucinoid dreams, which have been shown to be underpinned by NREM and REM polysomnographic patterns respectively (McNamara et al., 2010). Although a …