Are seasonality of mood and eveningness closely associated? Vincenzo Natale a, * , Ana Adan b , Paolo Scapellato a a Department of Psychology, University of Bologna, Viale Berti Pichat 5, I-40127 Bologna, Italy b Department of Psychiatry and Clinic on Psychobiology, University of Barcelona, Passeig de la Vall d’Hebron 171, E-08035 Barcelona, Spain Received 16 June 2004; received in revised form 13 October 2004; accepted 16 December 2004 Abstract It has been suggested that being an bevening typeQ might enhance susceptibility to non-seasonal and seasonal affective disorders (SAD). In a survey and a prospective study, we examine the relationship between mood seasonality and circadian typology. In the survey study, the Morningness–Eveningness Questionnaire (MEQ) and the Seasonal Pattern Assessment Questionnaire (SPAQ) were administered to 1715 university students from Spain and Italy. In the prospective study, 18 subjects, selected from the Italian sample, self-assessed their mood monthly for over a year. A slight but significant negative correlation between the MEQ score and the Global Seasonality Score was found in the survey study, with a significantly higher incidence of evening versus morning types among the students with seasonal depression. These results were not replicated when the Spanish sample was analysed separately. In the prospective study, evening types did not present a higher annual range of mood variations than morning types. Caution should be exercised in ascribing eveningness as a risk factor in SAD since other underestimated factors, including social–cultural conditions, might be involved in the pathogenesis of mood seasonality. D 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Human seasonal rhythms; Circadian typology; Seasonal affective disorder; Gender differences 1. Introduction Though our modern life style tends to mask envi- ronmental changes, the natural environment still plays an important role in modulating human mood and behaviour. This field of research has attracted increas- ing scientific interest since the identification of sea- sonal affective disorder (SAD) (Rosenthal et al., 1984b), a condition in which affective episodes (de- pression or mania) recur regularly during specific periods of the year. The onset of winter SAD (more common than summer SAD) is often associated with seasonal reduc- tions in daylight, with remissions tending to occur with subsequent seasonal increases in daylight. The incidence of winter SAD appears to be correlated to latitude, with a higher prevalence occurring at higher latitudes (i.e. greater annual daylight variations) 0165-1781/$ - see front matter D 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2004.12.010 * Corresponding author. Tel.: +39 51 2091846; fax: +39 51 243086. E-mail address: vincenzo.natale@unibo.it (V. Natale). Psychiatry Research 136 (2005) 51 – 60 www.elsevier.com/locate/psychres