Read on below to learn more about Pokémon Sleep:

Update Contents (version 1.0.3)

Thank you for playing Pokémon Sleep!
This update includes the following improvement.
• Reducing power consumption when tracking sleep without laying mobile device face down

The following issues have been resolved.
• Volume adjustments for Relaxing Sounds not working on certain devices
• Game becoming unable to proceed at beginning of Energy tutorial after pausing cooking tutorial
• Game freezing when accepting a friend request from someone with 50 friends

We sincerely apologize for the inconvenience.
We hope you continue to enjoy Pokémon Sleep.

Source: Official Pokémon Sleep news