Longitudinal Ecological Study on Sleep-Wake Patterns in MDD Using Actigraphy

Associations Between Actigraphy-Derived Sleep-Wake Patterns and Illness Trajectories and Treatment Response in Major Depressive Disorder

The proposed study will include a longitudinal ecological study (Study 1) and a randomised controlled trial (Study 2). The aims will be to (1) identify the sleep-wake profiles in individuals with Major Depressive Disorder (MDD) through clustering; (2) examine the associations between sleep-wake features/profiles and the prognosis of MDD; and (3) investigate the anti-depressant effects of sleep- and circadian-targeted intervention in those with MDD and whether sleep-wake features/profiles may moderate the treatment outcomes.

In Study 1, a total of 140 participants comprising 70 participants with MDD and 70 age- and gender-matched healthy controls will be recruited. Sleep-wake patterns will be collected for 4 consecutive weeks using actigraphy devices and one-off self-report measures will be collected via an in-house smartphone application, PsyHub.

Study 1 and 2 will follow the CONSORT and STROBE guidelines, respectively. The current registration is only for Study 1 of the current research project.

Inclusion Criteria for Healthy Control Group:

• Adults aged 18 to 65 years living in Hong Kong
• Being fluent and literate in Cantonese
• A Patient Health Questionnaire-9 (PHQ-9) score of below 5, indicating minimal or no depressive symptoms
• Accessibility to an Internet-enabled mobile device (iOS or Android operating system)
• Willingness to provide informed consent and comply with the trial protocol.

Exclusion Criteria for Healthy Control Group:

• Presence of any psychiatric disorder(s) as assessed by MINI
• Shift work, pregnancy, or work, family, or other commitments that interfere with regular sleep-wake patterns
• Presence of other untreated sleep disorders based on cut-off scores of individual sections in SLEEP-50.

We will not exclude those with current suicidal risks (i.e., non-fleeting intent or plan), which is a common symptom of MDD. However, if serious suicidal risk (i.e., PHQ-9 Item 9 score > 2) is identified, the participant will be referred to the PI (a clinical psychologist) for further assessment and professional mental health services if deemed necessary.

Inclusion Criteria for the Major Depressive Disorder (MDD) group:

• Adults aged 18-65 years living in Hong Kong
• Being fluent and literate in Cantonese
• A PHQ-9 score of at least 10, indicating a moderate level of depression.
• Meeting the DSM diagnostic criteria for current MDD according to the Mini International Neuropsychiatric Interview (MINI)
• Experiencing ≥ 1 sleep or circadian problem in the past 3 months according to the sleep and circadian problems checklist (i.e., time needed to fall asleep ≥ 30 minutes, wake after sleep onset ≥ 30 minutes, < 6-hour sleep per night or ≥ 9-hour sleep per night per 24-hour period, and falling asleep after 2:00 AM ≥ 3 nights per week; and variability in the sleep-wake schedule ≥ 2.78 hours within a week)
• Access to an Internet-enabled mobile device (iOS or Android operating system)
• Willingness to provide informed consent and comply with the trial protocol.

Exclusion Criteria for the Major Depressive Disorder (MDD) group:

• Severe medical or neurocognitive disorder(s) that make participation unsuitable based on the team's clinical experience
• Presence of other psychiatric disorders as assessed by MINI
• A history of electroconvulsive therapy (ECT)
• Current involvement in any psychological treatment programme that targets depression and/or sleep and circadian problems
• A change in the class or dose of any prescribed psychotropic drugs within 6 weeks before the baseline assessment
• Shift work, pregnancy, or work, family, or other commitments that interfere with regular sleep-wake patterns
• Presence of other untreated sleep disorders, including narcolepsy, obstructive sleep apnoea (OSA), and restless leg syndrome (RLS)/periodic leg movement disorder (PLMD) based on the cut-off scores of SLEEP-50 (narcolepsy ≥ 7; OSA ≥ 15; RLS/PLMD ≥ 7)