watchOS 11.4 added a “Break Through Silent Mode” option in Sound & Haptics.
Enable it and, if you wear your Apple Watch to bed, sound and haptics will play regardless of whether or not Silent Mode is toggled on. Before this, if Silent Mode was enabled, the Apple Watch would only use haptics as part of its alarm.
watchOS 11.4 can be downloaded through the dedicated Apple Watch app on the iPhone by going to General > Software Update. To install the new software, the Apple Watch needs to have at least 50% battery, needs to be placed on a charger, and it needs to be in range of the iPhone.