# Late-stage interventional trials reporting sleep-related outcomes in older adults with Parkinson’s disease: a ClinicalTrials.gov registry review

## TL;DR

This study reviews late-stage clinical trials on sleep issues in older adults with Parkinson’s disease, finding a focus on drugs and a lack of behavioral interventions or diverse participant inclusion.

## Contribution

The paper provides a first-of-its-kind descriptive analysis of late-stage interventional trials on sleep outcomes in older adults with Parkinson’s disease.

## Key findings

- Most trials focused on pharmacologic interventions like rotigotine and levodopa–carbidopa intestinal gel.
- Subjective sleep assessments were common, while objective measures like polysomnography were rarely used.
- No trials evaluated behavioral or circadian-based interventions such as cognitive-behavioral therapy or bright-light therapy.

## Abstract

Sleep disturbances are among the most disabling non-motor symptoms in Parkinson’s disease (PD), particularly affecting older adults, in whom age-related vulnerability and multimorbidity may exacerbate sleep dysfunction. Despite their high prevalence, interventional evidence reporting sleep-related outcomes in PD remains incompletely characterized, and methodological heterogeneity limits the comparability of findings across studies. This registry-based descriptive review aimed to characterize the landscape of late-stage interventional trials reporting sleep-related outcomes in PD, with attention to study design, older-adult eligibility, and intervention types.

A descriptive analysis of completed late-stage interventional studies registered on ClinicalTrials.gov was conducted. Late-stage was operationally defined as Phase III–IV interventional trials and explicitly linked open-label extension/rollover studies. Eligible studies permitted enrolment of adults aged ≥ 65 years with Parkinson’s disease and reported at least one sleep-related outcome. Extracted data included intervention type, study design, sleep outcome measures, and study duration.

Twenty-one trials met inclusion criteria. Most focused on dopaminergic or adjunctive pharmacologic interventions, including rotigotine, pramipexole, and levodopa–carbidopa intestinal gel. Reported sleep-related outcomes were primarily derived from subjective instruments such as the Parkinson’s Disease Sleep Scale (PDSS/PDSS-2) or SCOPA-Sleep, while objective assessments such as polysomnography or actigraphy were infrequently specified. No completed late-stage trials evaluating structured behavioral or circadian-oriented interventions, including cognitive-behavioral therapy for insomnia, exercise, or bright-light therapy, were identified. Eligibility criteria suggested that clinically vulnerable populations, including frail or cognitively impaired individuals, were likely underrepresented.

Late- stage interventional evidence reporting sleep-related outcomes in PD remains predominantly pharmacologic, short-term, and methodologically heterogeneous. The absence of completed behavioral or multimodal trials and eligibility criteria that may limit inclusion of clinically vulnerable individuals highlight important evidence gaps. Future research should prioritize inclusive, geriatric-informed, and multimodal designs incorporating both subjective and objective sleep measures.