File(s) not publicly available

Further evidence for the influence of photoperiod at birth on chronotype in a sample of German adolescents

journal contribution
posted on 06.12.2017, 00:00 by C Vollmer, C Randler, Vitale Di Milia
Individuals differ in their circadian preferences (chronotype). There is evidence in the literature to support a season-of birth effect on chronotype but the evidence is not convincing. In part, the relationship is obscured by a number of methodological differences between studies, including the measures used to define morningness, the way in which the seasons were categorized, and the sample size. This study adds to the literature in several ways. First, we adopt a new approach to categorizing the photoperiod rather than the calendar season; thus we prefer to use the term photoperiod at birth. Second, we used two measures of morningness. Third, we used a large and homogeneous German sample. The results show that adolescents (n = 2905) born during the increasing photoperiod (Feb–Apr) had a significantly later midpoint of sleep (MSFsc) than those born during the decreasing photoperiod (Aug–Oct). A similar pattern was found for the Composite Scale of Morningness (CSM). Furthermore, both measures of chronotype demonstrated a significant quadratic function over a 1-yr cycle. When looking at each of six consecutive years separately, the Composite Scale of Morningness suggests a cosine rhythm linked to increasing and decreasing photoperiods that becomes weaker in amplitude with increasing age. Despite the strengths in our study, the effect of photoperiod at birth on chronotype remains small. Future studies may require larger sample sizes, may need to explore how neonatal light exposure modulates chronotype, and may need to track how puberty and adolescent lifestyle habits mask the photoperiod effect.

History

Volume

29

Issue

10

Start Page

1345

End Page

1351

Number of Pages

7

eISSN

1525-6073

ISSN

0742-0528

Language

en-aus

Peer Reviewed

Yes

Open Access

No

External Author Affiliations

Institute for Health and Social Science Research (IHSSR); University of Education (Heidelberg, Germany);

Era Eligible

Yes

Journal

Chronobiology international : the journal of biological and medical rhythm research.

Exports