Set your alarm, Trainers! You don't want to sleep through this special Pokémon GO event. From May 28, 2019, at 6:00 p.m. PDT through June 3, 2019, at 1:00 p.m. PDT, you'll have the opportunity to encounter sleeping Snorlax in the wild. Once you catch one of these snoozing Pokémon, it will wake up and be itching for a battle, so take a photo during your encounter if you want a memento of Snorlax's dozing appearance. As a bonus, any Snorlax caught during this event will know the move Yawn, which Snorlax cannot normally learn.
Speaking of sleeping, don't miss a related announcement at the Pokémon 2019 Press Conference.
Good luck catching those wild Snorlax, Trainers! We appreciate your assistance in clearing the road of these lumbering loafers!