Age as a moderator of the association between depressive symptoms and morningness–eveningness Seog Ju Kim a , Yu Jin Lee a , Hyunkyung Kim a , In Hee Cho a , Jun-Young Lee b, ⁎ , Seong-Jin Cho a a Department of Psychiatry, Gachon University of Medicine and Science, Incheon, South Korea b Department of Psychiatry, Seoul National University Boramae Hospital College, Seoul, South Korea Received 23 October 2007; received in revised form 22 June 2009; accepted 26 June 2009 Abstract Objectives: We aimed to investigate the moderating effect of age on the association of morningness–eveningness with depression in subjects with a broad range of ages. The hypothesis of the current study was that there would be a relationship between depressive symptoms and eveningness, especially in young age groups. Methods: Three hundred sixty-one subjects (male/female=140/221) from 19 to 79 years of age participated in the study. Subjects were separated into five age groups: (1) ≤20s (n=70), (2) 30s (n=85), (3) 40s (n=97), (4) 50s (n=54) and 5) ≥60s (n=55). The Horne–Osteberg Morning- ness–Eveningness Questionnaire (MEQ) and the Center for Epidemiological Studies for Depression Scale (CES-D) were administered to all subjects. Results: MEQ showed a signifi- cantly independent and negative association with CES-D (β= -.27, Pb .001), which meant the association between eveningness and depressive symptoms. The negative association between MEQ and CES-D were significant in ≤20s (β=-.31, P=.01), 50s (β=-.38, Pb .01) and ≥60s (β=-.35, Pb .01), while there was no significant association between MEQ and CES-D in 30s (β=-.06, P=.56) and 40s (β=-.10, P=.32). Conclusion: Our findings demonstrate an association of depressive symptoms with eveningness, which was more prominent in younger or older aged than in middle aged. Our findings suggest that the association between depressive symptoms and eveningness might be moderated by age. © 2010 Elsevier Inc. All rights reserved. Keywords: Depression; Morningness–eveningness; Age Introduction Depression has been reported to be associated with disruption of various biological circadian rhythms such as sleep structure, body temperature and diurnal profile of hormones [1–3]. Depression may also be related to the preference of morning/day activity (i.e., morningness) or evening/night activity (i.e., eveningness), as the morning- ness–eveningness is another indicator for circadian rhythm [4,5]. Prior studies have reported that depression was associated with eveningness, a marker of phase delay [6–9]. Out- patients with major depressive disorder (MDD) have been reported to have higher eveningness [6]. An association between eveningness and depressive symptoms in the non- clinical population has also been reported [7–9]. These findings contradict with the phase advance hypothesis, which suggests that depression is associated with the advanced phase of circadian rhythm [2,10]. This discrepancy suggests the possibility that the circadian rhythm abnormal- ities in depression would be varied for each individual. However, moderating factors on the association between depression and eveningness have not been investigated yet. It is well known that morningness–eveningness is substantially affected by age. After the peak of eveningness Journal of Psychosomatic Research 68 (2010) 159 – 164 ⁎ Corresponding author. Department of Psychiatry, Seoul National University Boramae Hospital, 395 Sindaebang-2-dong, Dongjak-ku, Seoul, 156-707, South Korea. Tel.: +82 2 840 2772; fax: +82 2 831 2826. E-mail address: benji@snu.ac.kr (J.-Y. Lee). 0022-3999/09/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2009.06.010