Rest Devices, Inc. is a Boston-based startup that builds software and hardware for parents to help their babies sleep better. The Mimo Baby Sleep Tracker, the company’s flagship product, is a wearable device that tracks a baby’s live biometric sleep data and is sold nationwide at leading retailers. Rest is now working in partnership with Johnson & Johnson to pair its extensive data science capabilities with machine learning expertise to build Nod, a customized digital coaching platform, the first focus of which is infant sleep.