Appendix B — Developing Research, Emerging Studies & Ongoing Investigations
Pilot Study at Heinrich-Heine-Universität Düsseldorf
A noteworthy emerging investigation into sleep-based suggestion techniques is a pilot study conducted at the Institute for Clinical Psychology, Heinrich-Heine-Universität Düsseldorf (HHU).
This study examined application of the Sleep Talk® method to selective mutism — a childhood condition characterised by failure to speak in specific social situations despite intact language ability in others. [b1]
The research was structured as a six-month, longitudinal pilot with 20 preschool-aged children receiving supportive suggestions during sleep, administered by trained parents. Ongoing assessment used validated clinical measures of selective mutism severity as primary outcomes.
According to published summaries, the results indicated significant reductions in mutism symptoms and improvements in social behaviour over the treatment period, suggesting that the Sleep Talk® intervention may hold promise as a supplementary therapeutic approach. [b1]
While the full peer-reviewed article is indexed in Verhaltenstherapie & Verhaltensmedizin (2025, Vol. 46: 30–43), it remains inaccessible in full open text without subscription or university access. Nevertheless, the abstract clearly describes:
A significant reduction in clinical symptom severity during the intervention period.
Feasibility of parent-delivered sleep suggestion protocols over six months.
Improvements in social engagement and communicative behaviour. [b1]
This study represents one of the first structured attempts to investigate sleep-time suggestion in a clinical childhood population within a university research setting, moving beyond anecdotal or case-series reports into the realm of systematic pilot research.
Other Sleep and Behavioural Studies
Beyond the Düsseldorf pilot, the broader landscape of sleep-related behavioural research includes numerous investigations into:
Sleep’s role in memory consolidation and emotional processing.
Variations of suggestion-based approaches in clinical contexts (e.g., hypnosis in paediatric populations).
Non-traditional interventions influencing learning and emotional regulation during sleep.
However, very few registered clinical studies currently focus on structured sleep-time suggestion as a primary intervention, highlighting a gap in the literature where early exploratory work such as the HHU pilot may catalyse future investigations.
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