The Biometric Lock Trigger
The Apple Watch utilizes a security protocol known as “Wrist Detection.” By default, the watch uses the optical sensors on its rear casing to continuously verify that it is physically strapped to human skin. If you take the watch off, it instantly locks itself, requiring a passcode to access. While highly secure, this feature is incredibly problematic for users with heavy wrist tattoos (which block the optical sensor) or users who wear the watch loosely over a jacket sleeve. If the sensor cannot read your skin, it will constantly lock the device every five minutes, making it completely unusable. If you are willing to sacrifice automatic locking for usability, you must disable this hardware trigger.
How to Turn Off Wrist Detection
You can permanently sever the bridge between the optical sensor and the locking mechanism via the Passcode settings.
- Open the Settings app directly on your Apple Watch (the grey gear icon).
- Scroll down the main list and tap on Passcode.
- Scroll to the absolute bottom of the page.
- Locate the master toggle switch labeled Wrist Detection.
- Toggle this switch to the Off position.
- You will be presented with a severe warning explaining that disabling this feature will also disable Apple Pay, background heart rate tracking, and Fall Detection. Tap Turn Off to confirm.
Strict Manual Security
The change is instantaneous. The Apple Watch will completely terminate the background daemon responsible for analyzing the optical skin-contact telemetry. The operating system is now mathematically decoupled from the physical sensor array for security purposes. You can now wear the watch over a thick winter coat, or over heavy ink, and it will absolutely refuse to lock itself automatically. However, you are now strictly responsible for your own data security; the watch will remain unlocked until you manually lock it from the Control Center or take it off.