Impact of psychostimulants on pre-existing sleep disturbances in newly diagnosed adult ADHD: a preliminary prospective cohort study

Abstract

To evaluate the short-term and sustained associations between stimulant therapy and insomnia severity and sleep quality in newly diagnosed university students with attention-deficit/hyperactivity disorder (ADHD) and pre-existing sleep disturbances. 16-week prospective cohort study. Single-centre, university-based clinical assessment and treatment programme. Thirty-four stimulant-naïve university students with newly diagnosed ADHD and self-reported sleep disturbances. Initiation of methylphenidate-based or amphetamine-based stimulant treatment as part of usual clinical care. Changes in Insomnia Severity Index (ISI) and Pittsburgh Sleep Quality Index (PSQI) scores at baseline, 4 weeks and 16 weeks. Regression models examined the effects of methylphenidate-equivalent dose on ISI and PSQI changes, adjusting for baseline severity and sex. Inverse probability weighting was applied to address potential attrition bias. Higher stimulant doses were associated with greater reductions in insomnia severity and improved sleep quality at 4 weeks (p<0.01), with these relationships persisting at 16 weeks (p<0.05). Improvements appeared dose-related and were not mirrored by changes in ADHD symptom scores. Attrition rates were higher among lower-dose participants; however, weighted analyses confirmed the robustness of the findings. In this preliminary cohort, appropriately dosed, morning-administered stimulant therapy was associated with improved—rather than worsened—sleep outcomes in university students with newly diagnosed ADHD and pre-existing sleep difficulties. While causality cannot be inferred, these results suggest stimulants may support better sleep quality in this population.