With all dark mode browsing on Google, Google Fit users can switch to a darker theme to make the ring more vivid. In addition to the dark theme, the Google Fit app is being updated to track your sleep patterns by pairing with apps or fitness trackers that provide the tool.
Sleep patterns are now displayed with purple bars. How many hours do you sleep with? But it doesn't seem to show any specific details, such as deep, light sleep hours. When you start Google Fit, you can see all this information on your home screen.
Dark themes can be enabled by going to your profile and selecting Settings. Don't take your eyes off as Google just started updating and you should be able to turn it on next week. In the meantime, here's a guide on how to darken everything here.