The effect of circadian preferences on insomnia severity and depressive symptoms via sleep hygiene in older adults with depression and healthy controls

Abstract

Background The elderly population is increasing globally. Thus, researches focus on the causes and treatment of insomnia, a noteworthy ageing problem. This study aims to investigate the relationship between chronotype and insomnia and whether sleep hygiene mediates this relationship in older adults with depression (OAD). Methods We assessed subjective insomnia severity, sleep hygiene, chronotype, depressive symptoms, and anxiety symptoms of 82 OAD and 70 healthy controls using the Sleep Hygiene Index (SHI), Insomnia Severity Index (ISI), Morningness-Eveningness Questionnaire (MEQ), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI). Results The mediation effect of SHI and ISI scores were evaluated in the relationship between MEQ and BDI total scores in OAD. The results showed that MEQ performed its effect on BDI through ISI with full mediation (effect = -0.16, SE: 0.07, 95% CI: -0.3230 to -0.0336). The mediation effect of SHI and BDI scores were evaluated in the relationship between MEQ and ISI total scores in OAD. In this model, it was found that MEQ significantly performed its effect on ISI through SHI and BDI. BDI and SHI predicted the ISI variable as partial mediators (respectively, effect = -0.05, SE: 0.03, 95% CI: -0.1073 to -0.0100; effect = -0.06, SE: 0.02, 95% CI: -0.1051 to -0.0129). Conclusions Sleep hygiene practices could be essential for the natural functioning of the biological clock and the interrelation of depression and insomnia. Longitudinal follow-up studies of structured sleep hygiene approaches are needed in terms of cost-effectiveness, in OAD.