State- and trait-like variation in morning and evening components of morningness–eveningness in winter depression

Abstract

Purpose: Evening preference (eveningness) can be a risk factor for depression and a shift toward morning preference (morningness) can occur in response to treatment. A study of winter depression provides possibility to longitudinally evaluate state- and trait-like variation in morningness–eveningness during treatment in winter and remission in summer.

Material and methods: Female patients with winter depression and controls without a psychiatric history (n = 54 and 32 with mean age ± standard deviation of 34.4 ± 11.0 and 35.7 ± 9.5 years, respectively) were treated with two-hour bright light for a week during winter period. Some of them (n = 40 and 19, respectively) were then restudied in summer. Measures obtained during the winter period from patients before and after treatment were compared to those obtained from controls and from the same patients in the summer period. Among compared measures, there were self-assessments of state- and trait-like differences in morning and evening components of morningness–eveningness.

Results: The groups of depressed patients and controls differed in self-assessments of morning but not evening component of morningness–eveningness. The difference in state-like variation in morning component became non-significant after treatment and in summer. On the other hand, trait-like variation in this component demonstrated adequate test–retest (winter–summer) reliability, i.e. a shift toward trait-like eveningness persisted in patients in the summer.

Conclusions: The observed normalization of state-like variation in morning component of morning–evening preference can be mainly explained by the disappearance of such depressive symptoms as lack of energy, social withdrawal, loss of interest in once enjoyable activities, etc.

Keywords:

• Morningness–eveningness
• chronotype
• seasonal affective disorder
• diurnal rhythms

Acknowledgements

The author is indebted to Dr. Konstantin Danilenko for his valuable help in recruitment and interviewing the study participants.

Disclosure statement

The author reports no conflicts of interest.

Additional information

Funding

The study was supported by grants from the Russian Foundation for Basic Research (number 07-06-00263-а, number 10-06-00114-а, number 13-06-00042-a, and number 16-06-00235-a) and the Russian Foundation for Humanities (number 06-06-00375-a, number 12-06-18001-e, and number 15-06-10403-a).