Pokémon Sleep: is continuing to add new content and updates on a regular basis. Read on below to learn more:

Maintenance Currently Underway

Thank you for playing Pokémon Sleep!
The app is currently undergoing maintenance.
Please wait awhile until maintenance has been completed.
(You can still track your sleep during maintenance.)

Maintenance Period

Starts: 2025/01/15 22:30
Ends: 2025/01/16 03:00

Source: Official Pokémon Sleep news