Pokémon Sleep will undergo scheduled maintenance from Jan. 14 to 15 as the app updates to version 3.2.0, and players should plan ahead. During the maintenance window, you may not be able to start tracking sleep, which could disrupt daily routines and research progress. The update is expected to bring fixes and improvements, though access to core features will be limited while work is underway. If you rely on the app nightly, it is a good idea to check the timing and avoid starting a sleep session until maintenance is complete.
Source: Official Pokémon Sleep news and PokemonSleep.net