Increased Reward-Related Behaviors during Sleep and Wakefulness in Sleepwalking and Idiopathic Nightmares.
BACKGROUND
We previously suggested that abnormal sleep behaviors, i.e., as found in parasomnias, may often be the expression of increased activity of the reward system during sleep. Because nightmares and sleepwalking predominate during REM and NREM sleep respectively, we tested here whether exploratory excitability, a waking personality trait reflecting high activity within the mesolimbic dopaminergic (ML-DA) system, may be associated with specific changes in REM and NREM sleep patterns in these two sleep disorders.


METHODS
Twenty-four unmedicated patients with parasomnia (12 with chronic sleepwalking and 12 with idiopathic nightmares) and no psychiatric comorbidities were studied. Each patient spent one night of sleep monitored by polysomnography. The Temperament and Character Inventory (TCI) was administered to all patients and healthy controls from the Geneva population (n = 293).


RESULTS
Sleepwalkers were more anxious than patients with idiopathic nightmares (Spielberger Trait anxiety/STAI-T), but the patient groups did not differ on any personality dimension as estimated by the TCI. Compared to controls, parasomnia patients (sleepwalkers together with patients with idiopathic nightmares) scored higher on the Novelty Seeking (NS) TCI scale and in particular on the exploratory excitability/curiosity (NS1) subscale, and lower on the Self-directedness (SD) TCI scale, suggesting a general increase in reward sensitivity and impulsivity. Furthermore, parasomnia patients tended to worry about social separation persistently, as indicated by greater anticipatory worry (HA1) and dependence on social attachment (RD3). Moreover, exploratory excitability (NS1) correlated positively with the severity of parasomnia (i.e., the frequency of self-reported occurrences of nightmares and sleepwalking), and with time spent in REM sleep in patients with nightmares.


CONCLUSIONS
These results suggest that patients with parasomnia might share common waking personality traits associated to reward-related brain functions. They also provide further support to the notion that reward-seeking networks are active during human sleep.
Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland; Department of Neuroscience, University of Geneva, Geneva, Switzerland; Department of Psychiatry, University of Wisconsin, Madison, Wisconsin, United States of America.
Lampros
L
Perogamvros
Department of Neuroscience, University of Geneva, Geneva, Switzerland; Swiss Center for Affective Sciences, University of Geneva, Geneva, Switzerland.
Kristoffer
K
Aberg
Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland.
Marianne
M
Gex-Fabry
Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland.
Stephen
S
Perrig
Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America.
C Robert
CR
Cloninger
Department of Neuroscience, University of Geneva, Geneva, Switzerland; Swiss Center for Affective Sciences, University of Geneva, Geneva, Switzerland.
Sophie
S
Schwartz
D000328:Adult; D002605:Character; D004325:Dreams; D005260:Female; D006801:Humans; D007175:Impulsive Behavior; D008297:Male; D008875:Middle Aged; D020184:Night Terrors / Q000503:physiopathology / Q000523:psychology*; D020447:Parasomnias / Q000503:physiopathology / Q000523:psychology*; D010555:Personality Inventory; D017286:Polysomnography; D012201:Reward; D012890:Sleep; D013009:Somnambulism / Q000503:physiopathology / Q000523:psychology*; D013694:Temperament; D014851:Wakefulness; D055815:Young Adult