There appears to be a hidden way to enable Night Shift mode on Apple Watch. First discovered by a Reddit user, you can use Siri to enable Night Shift on your Apple Watch.

When asked to turn on Night Shift, Siri will comply and reduce the amount of blue light on the Apple Watch. The screen will dim and take on a yellowish tint that reduces blue light exposure.

There is no other option or switch to do this. Only through Siri can you turn on Night Shift on the Apple Watch.

Apple also doesn’t have any documentation for enabling Night Shift on the Apple Watch, suggesting it was introduced by accident. Not all Apple Watch models can enable Night Shift by asking Siri. The feature is reportedly not available on Apple Watch Series 5 and older.