In sleep mode, time and sleep icon as well as a summary are visible on the screen of the iHealth Wave.
If you wake up during the night, you can check the time on your iHealth Wave. Make a frirm rotation of your wrist to "wake up" the iHealth Wave. The time and sleep icone are displayed for 4 seconds and a summary of your sleep done so far is displayed for 3 seconds.
*credit to Sylvain of iHealth Labs EU