AutoSleep vs Sara by Comma

AutoSleep is a sleep-tracking app for Apple Watch and iPhone that records sleep automatically in the background, without requiring the user to start or stop a session. It uses heart rate, motion, and (where available) blood oxygen and wrist temperature data to estimate sleep stages, sleep quality, and a running sleep debt total called the sleep bank. The app integrates with Apple Health and HomeKit, offers a smart alarm that wakes users during a lighter sleep phase, and includes an add-on companion app, AutoSnore, for snore detection. It is sold as a single one-time purchase on the App Store rather than a subscription, and processes data on-device rather than through a cloud account.

Sara is a reproductive health tracking platform from the period-care company Comma, built as a progressive web app rather than a downloadable app store product. It lets users log cycles and symptoms, spot patterns over time, and securely share that data with a healthcare provider when they choose to. Comma designed Sara around the idea that period data deserves clinical-grade privacy: the company states it holds itself to HIPAA as a benchmark for data protection and never sells user data, distinguishing it from many mainstream period trackers that monetize user data. It launched alongside a seed funding round aimed at bringing more personalized science to reproductive health.

• One-time purchase price with no ongoing subscription fees
• Fully automatic tracking that does not require remembering to start or stop a sleep session
• Detailed metrics including sleep stages, SpO2, respiration rate, and wrist temperature on supported hardware
• On-device processing with no account or login required for basic use

• Strong stated privacy and data-protection commitments
• No app store download or tracking footprint
• Designed specifically to support conversations with healthcare providers
• Backed by a company focused solely on reproductive health

• Requires an Apple Watch for automatic tracking; iPhone-only use is far more limited
• Advanced metrics like SpO2 and respiration depend on specific newer Apple Watch models
• Interface and terminology (sleep bank, sleep debt) have a learning curve for new users

• No native iOS or Android app, only a browser-based PWA
• Pricing and premium features are not disclosed on the site
• Smaller company with less track record than major period-tracking apps
• Feature depth such as fertility prediction detail is less documented publicly