If you have trouble sleeping, start with "Hello Google, I can't sleep." It will react with some options – nature sounds, surrounding music or sleepy playlists that will help you fall asleep. The only thing that doesn't help with that: nightmares.
Things you can say toto help you get sleepy:
"Hello Google, play relaxing music."
Google finds a playlist of surrounding music on YouTube Music, Google Play Music, Spotify, Pandora or Deezer if you have an account (if not, these services have all the free options). If you like the playlist, open the music app to save it. You can link your media accounts when you set up your speaker or at any time using the Google homepage.
"Hello Google, play relaxing nature sounds."
You can make the request a few times until you can handle the sound you want. Some of the options I came across were rainfall, a babbling stream, crickets and chirping birds. Be careful with the water noise at night, if you don't want a bathroom break too! The Google homepage can also play a natural audio playlist from your linked music apps.
"Hello Google, tell me a bedtime story."
I'm a fan of falling asleep to podcasts or TV shows. If your little one is having trouble catching some Z, try the Google Home Bedtime History option. The stories are child-focused but can give some background noise for children of all ages to fly to. Google Home selects short stories from Google Play Books and Storynory. You can sort between 3-10 minute fairy tales, snap stories or shorts on popular TV characters like Dora the Explorer.
"Hello Google, sing me a lullaby."
Another option to help kids get ready for bed, Google can sing or play a cradle. You will find classics like Twinkle, Twinkle Little Star, a German rock song and Rock-a-bye Baby with a reworked (less violent) end.