Study objectives: We investigated whether sleep disruption and circadian preference mediate the associations of ADHD symptom severity with depression symptom severity and quality of life. Methods: 1364 participants (mean: 51.86 [SD = 0.37] years, 75% females) from a large-scale cross-sectional online survey (Netherlands Sleep Registry) completed a sociodemographic questionnaire, the Adult ADHD Rating Scale, Hospital Anxiety and Depression Scale (HADS), Satisfaction With Life Scale (SLS) and Cantril Ladder (CL) (quality of life measures), Insomnia Severity Index, Pittsburgh Sleep Quality Index, and Munich Chronotype Questionnaire. Results: Higher ADHD symptom severity was significantly associated with depression severity (p = 0.03), lower quality of life (p < 0.001), insomnia severity (p < 0.001), lower sleep quality (p < 0.001), and later circadian preference (p = 0.01). No sleep or circadian factor significantly mediated the association of the severity of symptoms of ADHD and depression (all p > 0.1). Conversely, only insomnia severity significantly mediated the association of the severity of symptoms of ADHD and quality of life (SLS: standardized beta = -0.10, 95% CI = [-0.12, -0.04]; CL: standardized beta = .103, 95% CI = [0.04, 0.16]). Conclusion: ADHD symptom severity was associated with lower quality of life, primarily mediated by insomnia symptom severity. Future studies targeting insomnia complaints in this population may help mitigate their depression complaints and improve their quality of life.

The authors have declared no competing interest.

The Netherlands Organization for Scientific Research (The Hague; VICI innovation grant no. 45307001) and the European Research Council (no. ERCADG2014671084 INSOMNIA) supported this work.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Volunteers of the NSR participated anonymously without revealing their names and addresses, and were not exposed to interventions or behavioral constraints. The NSR therefore does not fall under the Dutch Medical Research Involving Human Subjects Act, and signed informed consent is not mandatory, as confirmed by the Medical Ethical Committee of the Academic Medical Center of the University of Amsterdam as well as the Central Committee on Research Involving Human Subjects (CCMO), The Hague, The Netherlands. Before performing this secondary data analysis, we obtained ethical approval by the University of Southampton Research Ethics Committee.

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Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

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The data that support the findings of this study are available from the shared senior author and Principal Investigator, [E.V.S.], upon reasonable request.