TOKYO, Feb 28, 2023 (BSS/AFP) - Pokemon's last major smartphone hit, "Pokemon Go", had fans on the move hunting the lovable characters, but its next release will focus on a more relaxing activity: sleep.

The Pokemon Company has revealed it will release "Pokemon Sleep" across most of the world in summer 2023, four years after it first announced plans for the game.

"Turn your sleep into entertainment," the company said in a press release late Monday.

Trailers for the new game suggest it combines a smartphone sleep tracker with gaming.

"Your adventure takes place on a small island where you'll carry out research on how Pokemon sleep. You'll work with a large Snorlax who lives on the island and Neroli, a professor who's studying Pokemon sleep styles."

"The longer you sleep, the higher your score in the morning, and the more Pokemon you'll see appear around Snorlax," the company said, urging players to "rest your very best!"

Fans will also be able to buy a "Pokemon GO Plus +" -- a Pokeball-shaped gadget that users can place by their pillow, with Pikachu's voice offering "cute prompts when it's time to wake up or go to sleep".

The company's "Pokemon Go" game, which saw players track down the "pocket monsters" using their phones, was an international phenomenon.

The free game uses satellite locations, graphics and camera capabilities to overlay cartoon characters on real-world settings, challenging players to capture and train the creatures.

But players were blamed for traffic accidents and other violations as they roamed the streets, buried in their phones.

Pokemon has been a global hit since it was launched as a role-playing game in 1996 for Nintendo's Game Boy console.

The franchise, whose slogan is "Gotta Catch 'Em All", also includes movies and a hugely popular animated TV show.