Martin Siniawski, CEO and co-founder, RestIgnacio, CTO, RestDiscovered the sleep use case from podcast app user behavior (10% of users, but high willingness to pay)Used jobs-to-be-done research to identify "DIY sleep hackers" as an underserved segmentChose CBTI (Cognitive Behavioral Therapy for Insomnia) as their foundation—a clinically proven approach with 80% efficacyEvolved from text chatbot to voice-first AI using Vapi for voice and OpenAI for reasoningBuilt a memory system that remembers user context (like traveling, having a dog) with time-based relevanceCreated dynamic agendas that drive daily conversations based on sleep data, program stage, and user complianceManaged parallel development paths (text via OpenAI Assistants and voice via Vapi)Moved from massive system prompts to RAG for general sleep knowledge, keeping user data in promptsNavigated wellness vs. medical product positioning with clear guardrails against diagnosis and medication adviceUsed weekly error analysis with domain experts (sleep therapists) to drive product iterationsBuilt LLM-powered evals for safety boundaries and experimented with Hamming for voice testingRest – AI sleep coach appVapi – Voice agent platform Rest usesLangfuse – Observability and evals platformHamming – Voice testing platformAI Evals Maven Course by Hamel Husain and Shreya Shankar (Get 35% off with Teresa's affiliate link)Chapters
00:00 Introduction to Rest and Its Founders
00:33 The Origin Story of the AI Sleep Coach
02:07 Exploring the Podcast App and Sleep Use Case
03:35 Transitioning to a Dedicated Sleep Audio App
05:47 Understanding User Segments and Sleep Challenges
07:45 Introduction to the AI Sleep Coach
13:14 The Role of Voice in the AI Sleep Coach
18:46 Daily User Interaction and Features
21:30 Prototyping and Early Learnings
28:09 Navigating Ethical and Regulatory Concerns
30:39 Navigating the Line Between Health and Wellness Apps
31:00 Incorporating Adjacent Disciplines into the App
32:15 The Power of 24/7 Availability
32:53 Evolution of the Chatbot and Error Analysis
34:49 User Experience Improvements and Voice Integration
46:49 Implementing Memory and Personalization
50:18 Dynamic Agenda and User-Centric Conversations
57:37 Evaluation and Guardrails
01:00:05 Future Roadmap and Enhancements
01:03:38 Combining Data Layers for Enhanced AI
01:06:00 Conclusion and Final Thoughts