The Apple Watch has a low-power mode that only tells the time
 

If you're jonesing for an Apple Watch, you probably want to do a lot with it. But what if you're headed out to a party and would rather not risk staring at a dead screen when you're wondering how late it is? Don't worry, you're covered. The New York ...

http://www.engadget.com/2015/03/01/a...=rss_truncated