Two options are available:

 1 - Preset sleep time:

- Open ZeCircle App

- Go to Settings > Advanced Settings > tap Preset Sleep to enter your desired bed and wake up times.

 By default, ZeCircle will track your sleep from 11pm until 7am

2 - Start / Exit sleep from ZeCircle app

- Open ZeCircle App

- Tap on the bottom purple sleep bar

- Click on Add sleep > Start sleep now

- To end sleep, open ZeCircle App, tap on the bottom purple sleep bar, click on Add sleep > Awake