Use Your Old Apple Watch as a Sleep-Tracking Tool
Sleep tracking is one of the most practical reasons to keep an old Apple Watch around. The biggest downside to sleeping with an Apple Watch has always been figuring out when to charge it. Although Apple has improved charging times and battery life on newer Apple Watch models, that may still not be enough for people with very active lifestyles.
If you wear your main Apple Watch all day, and then want to wear it all night too, you eventually run into that awkward moment when you can’t fully charge it before leaving.
A second Apple Watch solves that problem in a very clean way. One charges while the other stays on your wrist. Then you switch back in the morning. If your old watch still has enough battery to make it through the night comfortably, it can become the dedicated sleep watch while your main one handles daytime use. You’ll get the benefits of sleep tracking without any worries in the morning.
As long as you have your sleep routine set up, your old Apple Watch will begin tracking automatically.

