How do I set Sleep Mode?

After Sleep Mode is enabled, the watch does not vibrate to remind you when it receives incoming calls, text messages, and other alerts. The Activate on Raise and Always On Display features will be disabled, and the screen brightness is forced down. Sleep Screen will show when you wake the screen.

Swipe down on the watch face and tap the Sleep Mode icon to enter Sleep Mode. You can also go to the app list and tap Settings > Preferences > Sleep Mode to enable/disable Sleep Mode.