ISSN 0033-2941 DOI 10.2466/09.16.PR0.113x19z4 © Psychological Reports 2013 Psychological Reports: Mental & Physical Health EFFECTS OF PROLONGED WAKEFULNESS: THE ROLE OF PERIOD3 GENOTYPES AND PERSONALITY TRAITS 1 GIUSEPPE BARBATO, ANTONIO COSTANZO, CIRO DELLA MONICA Department of Psychology Second University of Naples, Italy PAOLO D'ONOFRIO Stress Research Institute University of Stockholm, Sweden FLAVIA CERRATO Department of Environmental Science Second University of Naples, Italy VITTORIA DE PADOVA Department of Psychology Second University of Naples, Italy Summary.—The roles of personality traits, as assessed by Eysenck Personality Inventory, and of the clock gene PERIOD3 (PER3) were analysed on the subjective effects of prolonged wakefulness. A sample of 70 healthy participants (7 men, 63 women; M age = 24.2 yr., SD = 3.2) was studied during forced wakefulness between 7:30 p.m. and 9:30 a.m. According to Eysenck's arousal model, it was hypothesized that prolonged wakefulness might affect in a different way those classified as Intro- verted and Extraverted. During the forced wakefulness period, the Introverted group showed greater decrease in subjective measures of vigilance than did the Extraverted group, but no differences were observed between groups with high and low scores on Psychoticism and Neuroticism. Prolonged wakefulness had a negative effect on subjective sleepiness and mood in all three PER3 polymorphisms analysed. Sleep deprivation is a sleep–wake manipulation used to test sleep functions. Deprivation affects different neuro-cognitive systems, produc- ing impairments on vigilance, working memory, and executive functions (Dinges & Kribbs, 1991; Harrison & Horne, 1998). Although agreement exists in literature on negative consequences of sleep deprivation, inter- individual differences have been observed, with some individuals show- ing great sensitivity to sleep loss while others are less affected (Van Dongen, Baynard, Maislin, & Dinges, 2004; Caldwell, Mu, Smith, Mishory, Caldwell, Peters, et al., 2005; Van Dongen, Vitellaro, & Dinges, 2005). Personality traits and genetic factors have been suggested to explain such differences. The seminal work of Corcoran (1962, 1972) showed that during sleep deprivation extraverts had a progressive deterioration on 2013, 113, 2, 1-12. 1 Address correspondence to Dr. Giuseppe Barbato, Department of Psychology, Second University of Naples, Viale Ellittico 31, 81100, Caserta, Italy or e-mail (Giuseppe.Barbato@ unina2.it).